# Koldflux

> Free, browser-based tools for short-form video creators, plus a dated reference of social platform specifications. Every tool runs client-side: files are never uploaded, there is no account, no queue, no daily limit and no watermark.

Platform specification data last reviewed (partial source coverage): 12 September 2026.
Machine-readable specifications: https://koldflux.com/api/specs.json (CC BY 4.0, no key required).

## Reference data

- [Social media video specs](https://koldflux.com/tools/specs): aspect ratio, maximum duration, file size, caption limit and safe zone for 10 platforms, in one dated table.
- [Specifications as JSON](https://koldflux.com/api/specs.json): the same data machine-readable, licensed CC BY 4.0.
- [Social media image sizes](https://koldflux.com/tools/image-size): exact pixel dimensions for 34 assets (banners, thumbnails, profile pictures, stories, posts).
- [About and verification method](https://koldflux.com/tools/about): how the data is checked and what the known limitations are.

## Per-platform tools

- **[TikTok](https://koldflux.com/tools/tiktok)** (9:16, 1080x1920, up to 10 minutes via the Content Posting API; account limits vary, caption limit 2200): [Spec cheat sheet](https://koldflux.com/tools/tiktok/spec), [Safe zone overlay](https://koldflux.com/tools/tiktok/safe-zone), [Caption limit checker](https://koldflux.com/tools/tiktok/caption-limit-checker), [Video length checker](https://koldflux.com/tools/tiktok/video-length-checker), [Best time to post](https://koldflux.com/tools/tiktok/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/tiktok/crop-video), [Compress video for this platform](https://koldflux.com/tools/tiktok/compress-video), [Trim video for this platform](https://koldflux.com/tools/tiktok/trim-video), [Resize image for this platform](https://koldflux.com/tools/tiktok/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/tiktok/format/mov), [does it support WEBM?](https://koldflux.com/tools/tiktok/format/webm), [does it support AVI?](https://koldflux.com/tools/tiktok/format/avi), [does it support MKV?](https://koldflux.com/tools/tiktok/format/mkv), [does it support GIF?](https://koldflux.com/tools/tiktok/format/gif)
- **[Instagram Reels](https://koldflux.com/tools/instagram-reels)** (9:16, 1080x1920, current limit not reverified; check the Reels composer, caption limit 2200): [Spec cheat sheet](https://koldflux.com/tools/instagram-reels/spec), [Safe zone overlay](https://koldflux.com/tools/instagram-reels/safe-zone), [Caption limit checker](https://koldflux.com/tools/instagram-reels/caption-limit-checker), [Video length checker](https://koldflux.com/tools/instagram-reels/video-length-checker), [Best time to post](https://koldflux.com/tools/instagram-reels/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/instagram-reels/crop-video), [Compress video for this platform](https://koldflux.com/tools/instagram-reels/compress-video), [Trim video for this platform](https://koldflux.com/tools/instagram-reels/trim-video), [Resize image for this platform](https://koldflux.com/tools/instagram-reels/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/instagram-reels/format/mov), [does it support WEBM?](https://koldflux.com/tools/instagram-reels/format/webm), [does it support AVI?](https://koldflux.com/tools/instagram-reels/format/avi), [does it support MKV?](https://koldflux.com/tools/instagram-reels/format/mkv), [does it support GIF?](https://koldflux.com/tools/instagram-reels/format/gif)
- **[YouTube Shorts](https://koldflux.com/tools/youtube-shorts)** (9:16 or 1:1, 1080x1920, up to 3 minutes, caption limit 5000): [Spec cheat sheet](https://koldflux.com/tools/youtube-shorts/spec), [Safe zone overlay](https://koldflux.com/tools/youtube-shorts/safe-zone), [Caption limit checker](https://koldflux.com/tools/youtube-shorts/caption-limit-checker), [Video length checker](https://koldflux.com/tools/youtube-shorts/video-length-checker), [Best time to post](https://koldflux.com/tools/youtube-shorts/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/youtube-shorts/crop-video), [Compress video for this platform](https://koldflux.com/tools/youtube-shorts/compress-video), [Trim video for this platform](https://koldflux.com/tools/youtube-shorts/trim-video), [Resize image for this platform](https://koldflux.com/tools/youtube-shorts/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/youtube-shorts/format/mov), [does it support WEBM?](https://koldflux.com/tools/youtube-shorts/format/webm), [does it support AVI?](https://koldflux.com/tools/youtube-shorts/format/avi), [does it support MKV?](https://koldflux.com/tools/youtube-shorts/format/mkv), [does it support GIF?](https://koldflux.com/tools/youtube-shorts/format/gif)
- **[LinkedIn](https://koldflux.com/tools/linkedin)** (16:9 or 9:16, 1920x1080, up to 15 minutes for organic video, caption limit 3000): [Spec cheat sheet](https://koldflux.com/tools/linkedin/spec), [Safe zone overlay](https://koldflux.com/tools/linkedin/safe-zone), [Caption limit checker](https://koldflux.com/tools/linkedin/caption-limit-checker), [Video length checker](https://koldflux.com/tools/linkedin/video-length-checker), [Best time to post](https://koldflux.com/tools/linkedin/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/linkedin/crop-video), [Compress video for this platform](https://koldflux.com/tools/linkedin/compress-video), [Trim video for this platform](https://koldflux.com/tools/linkedin/trim-video), [Resize image for this platform](https://koldflux.com/tools/linkedin/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/linkedin/format/mov), [does it support AVI?](https://koldflux.com/tools/linkedin/format/avi)
- **[Pinterest](https://koldflux.com/tools/pinterest)** (9:16, 1080x1920, 4 seconds to 5 minutes for an organic Video Pin, caption limit 800): [Spec cheat sheet](https://koldflux.com/tools/pinterest/spec), [Safe zone overlay](https://koldflux.com/tools/pinterest/safe-zone), [Caption limit checker](https://koldflux.com/tools/pinterest/caption-limit-checker), [Video length checker](https://koldflux.com/tools/pinterest/video-length-checker), [Best time to post](https://koldflux.com/tools/pinterest/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/pinterest/crop-video), [Compress video for this platform](https://koldflux.com/tools/pinterest/compress-video), [Trim video for this platform](https://koldflux.com/tools/pinterest/trim-video), [Resize image for this platform](https://koldflux.com/tools/pinterest/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/pinterest/format/mov), [does it support WEBM?](https://koldflux.com/tools/pinterest/format/webm), [does it support GIF?](https://koldflux.com/tools/pinterest/format/gif)
- **[X (Twitter)](https://koldflux.com/tools/x)** (16:9 or 1:1, 1920x1080, up to 2 minutes 20 seconds for most accounts, caption limit 280): [Spec cheat sheet](https://koldflux.com/tools/x/spec), [Safe zone overlay](https://koldflux.com/tools/x/safe-zone), [Caption limit checker](https://koldflux.com/tools/x/caption-limit-checker), [Video length checker](https://koldflux.com/tools/x/video-length-checker), [Best time to post](https://koldflux.com/tools/x/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/x/crop-video), [Compress video for this platform](https://koldflux.com/tools/x/compress-video), [Trim video for this platform](https://koldflux.com/tools/x/trim-video), [Resize image for this platform](https://koldflux.com/tools/x/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/x/format/mov), [does it support WEBM?](https://koldflux.com/tools/x/format/webm), [does it support GIF?](https://koldflux.com/tools/x/format/gif)
- **[Facebook Reels](https://koldflux.com/tools/facebook-reels)** (9:16, 1080x1920, no single Reel length cap in the unified video publishing flow, caption limit 63206): [Spec cheat sheet](https://koldflux.com/tools/facebook-reels/spec), [Safe zone overlay](https://koldflux.com/tools/facebook-reels/safe-zone), [Caption limit checker](https://koldflux.com/tools/facebook-reels/caption-limit-checker), [Video length checker](https://koldflux.com/tools/facebook-reels/video-length-checker), [Best time to post](https://koldflux.com/tools/facebook-reels/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/facebook-reels/crop-video), [Compress video for this platform](https://koldflux.com/tools/facebook-reels/compress-video), [Trim video for this platform](https://koldflux.com/tools/facebook-reels/trim-video), [Resize image for this platform](https://koldflux.com/tools/facebook-reels/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/facebook-reels/format/mov), [does it support WEBM?](https://koldflux.com/tools/facebook-reels/format/webm), [does it support AVI?](https://koldflux.com/tools/facebook-reels/format/avi), [does it support GIF?](https://koldflux.com/tools/facebook-reels/format/gif)
- **[Snapchat Spotlight](https://koldflux.com/tools/snapchat)** (9:16, 1080x1920, current maximum not established by the Spotlight help page, caption limit 250): [Spec cheat sheet](https://koldflux.com/tools/snapchat/spec), [Safe zone overlay](https://koldflux.com/tools/snapchat/safe-zone), [Caption limit checker](https://koldflux.com/tools/snapchat/caption-limit-checker), [Video length checker](https://koldflux.com/tools/snapchat/video-length-checker), [Best time to post](https://koldflux.com/tools/snapchat/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/snapchat/crop-video), [Compress video for this platform](https://koldflux.com/tools/snapchat/compress-video), [Trim video for this platform](https://koldflux.com/tools/snapchat/trim-video), [Resize image for this platform](https://koldflux.com/tools/snapchat/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/snapchat/format/mov)
- **[Threads](https://koldflux.com/tools/threads)** (9:16 or 1:1, 1080x1920, up to 5 minutes, caption limit 500): [Spec cheat sheet](https://koldflux.com/tools/threads/spec), [Safe zone overlay](https://koldflux.com/tools/threads/safe-zone), [Caption limit checker](https://koldflux.com/tools/threads/caption-limit-checker), [Video length checker](https://koldflux.com/tools/threads/video-length-checker), [Best time to post](https://koldflux.com/tools/threads/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/threads/crop-video), [Compress video for this platform](https://koldflux.com/tools/threads/compress-video), [Trim video for this platform](https://koldflux.com/tools/threads/trim-video), [Resize image for this platform](https://koldflux.com/tools/threads/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/threads/format/mov)
- **[Instagram Feed](https://koldflux.com/tools/instagram-feed)** (1:1 or 4:5, 1080x1350, depends on the video publishing surface; current limit not reverified, caption limit 2200): [Spec cheat sheet](https://koldflux.com/tools/instagram-feed/spec), [Safe zone overlay](https://koldflux.com/tools/instagram-feed/safe-zone), [Caption limit checker](https://koldflux.com/tools/instagram-feed/caption-limit-checker), [Video length checker](https://koldflux.com/tools/instagram-feed/video-length-checker), [Best time to post](https://koldflux.com/tools/instagram-feed/best-time-to-post), [Crop video for this platform](https://koldflux.com/tools/instagram-feed/crop-video), [Compress video for this platform](https://koldflux.com/tools/instagram-feed/compress-video), [Trim video for this platform](https://koldflux.com/tools/instagram-feed/trim-video), [Resize image for this platform](https://koldflux.com/tools/instagram-feed/resize-image). Format compatibility: [does it support MOV?](https://koldflux.com/tools/instagram-feed/format/mov), [does it support WEBM?](https://koldflux.com/tools/instagram-feed/format/webm), [does it support AVI?](https://koldflux.com/tools/instagram-feed/format/avi), [does it support GIF?](https://koldflux.com/tools/instagram-feed/format/gif)

## File converters

- **Video** (42 pairs): [MP4 to WebM](https://koldflux.com/tools/convert/video/mp4-to-webm), [MP4 to MOV](https://koldflux.com/tools/convert/video/mp4-to-mov), [MP4 to MKV](https://koldflux.com/tools/convert/video/mp4-to-mkv), [MP4 to AVI](https://koldflux.com/tools/convert/video/mp4-to-avi), [MP4 to GIF](https://koldflux.com/tools/convert/video/mp4-to-gif), [WebM to MP4](https://koldflux.com/tools/convert/video/webm-to-mp4) - full list at https://koldflux.com/tools/convert/video
- **Audio** (42 pairs): [MP3 to WAV](https://koldflux.com/tools/convert/audio/mp3-to-wav), [MP3 to AAC](https://koldflux.com/tools/convert/audio/mp3-to-aac), [MP3 to OGG](https://koldflux.com/tools/convert/audio/mp3-to-ogg), [MP3 to FLAC](https://koldflux.com/tools/convert/audio/mp3-to-flac), [MP3 to M4A](https://koldflux.com/tools/convert/audio/mp3-to-m4a), [WAV to MP3](https://koldflux.com/tools/convert/audio/wav-to-mp3) - full list at https://koldflux.com/tools/convert/audio
- **Image** (6 pairs): [PNG to JPEG](https://koldflux.com/tools/convert/image/png-to-jpg), [PNG to WebP](https://koldflux.com/tools/convert/image/png-to-webp), [JPEG to PNG](https://koldflux.com/tools/convert/image/jpg-to-png), [JPEG to WebP](https://koldflux.com/tools/convert/image/jpg-to-webp), [WebP to PNG](https://koldflux.com/tools/convert/image/webp-to-png), [WebP to JPEG](https://koldflux.com/tools/convert/image/webp-to-jpg) - full list at https://koldflux.com/tools/convert/image
- **Video to audio** (46 pairs): [MP4 to MP3](https://koldflux.com/tools/convert/video-to-audio/mp4-to-mp3), [MP4 to WAV](https://koldflux.com/tools/convert/video-to-audio/mp4-to-wav), [MP4 to AAC](https://koldflux.com/tools/convert/video-to-audio/mp4-to-aac), [MP4 to OGG](https://koldflux.com/tools/convert/video-to-audio/mp4-to-ogg), [MP4 to FLAC](https://koldflux.com/tools/convert/video-to-audio/mp4-to-flac), [MP4 to M4A](https://koldflux.com/tools/convert/video-to-audio/mp4-to-m4a) - full list at https://koldflux.com/tools/convert/video-to-audio

## Aspect ratio

- [9:16](https://koldflux.com/tools/aspect-ratio/video/9-16), [16:9](https://koldflux.com/tools/aspect-ratio/video/16-9), [1:1](https://koldflux.com/tools/aspect-ratio/video/1-1), [4:5](https://koldflux.com/tools/aspect-ratio/video/4-5), [4:3](https://koldflux.com/tools/aspect-ratio/video/4-3), [21:9](https://koldflux.com/tools/aspect-ratio/video/21-9) (video and image, index at https://koldflux.com/tools/aspect-ratio)

## Text tools

- [Fancy text generator](https://koldflux.com/tools/text/fancy-text): Turn plain text into bold, italic, monospace, circled, squared, fullwidth, strikethrough or underlined Unicode styles you can paste into any bio or caption.
- [Case converter](https://koldflux.com/tools/text/case-converter): Convert text to UPPERCASE, lowercase, Title Case, Sentence case or aLtErNaTiNg case instantly in your browser.
- [Remove line breaks](https://koldflux.com/tools/text/remove-line-breaks): Strip hard line breaks out of pasted text so it flows as clean paragraphs again. Free, runs in your browser.
- [Remove emoji](https://koldflux.com/tools/text/remove-emoji): Strip every emoji and pictograph out of a block of text, leaving the words untouched.
- [Hashtag counter](https://koldflux.com/tools/text/hashtag-counter): Count how many hashtags a caption contains and list them, so you stay inside platform limits.
- [Word counter](https://koldflux.com/tools/text/word-counter): Count words, characters, sentences and estimated reading and speaking time for any text.
- [Text repeater](https://koldflux.com/tools/text/text-repeater): Repeat a word or phrase any number of times, with an optional separator.
- [Reverse text](https://koldflux.com/tools/text/reverse-text): Reverse text character by character or flip the order of the words.

## Single-purpose media tools

- [Mute video](https://koldflux.com/tools/video/mute)
- [Rotate video](https://koldflux.com/tools/video/rotate)
- [Change video speed](https://koldflux.com/tools/video/speed)
- [Compress a video](https://koldflux.com/tools/video/compress)
- [Crop a video by exact pixels](https://koldflux.com/tools/video/crop)
- [Trim a video between timestamps](https://koldflux.com/tools/video/trim)
- [Trim audio](https://koldflux.com/tools/audio/trim)
- [Normalize audio loudness](https://koldflux.com/tools/audio/normalize)
- [Remove silence from audio](https://koldflux.com/tools/audio/silence-remove)
- [Compress image](https://koldflux.com/tools/image/compress)
- [Compress an image to a target file size](https://koldflux.com/tools/image/target-size)
- [QR code generator](https://koldflux.com/tools/qr-code)
- [Merge videos](https://koldflux.com/tools/video/merge)
- [Add a watermark to a video](https://koldflux.com/tools/video/watermark)

## Guides

- [MP4 vs WebM: which one should you actually use?](https://koldflux.com/tools/guides/mp4-vs-webm): MP4 wins on compatibility, WebM wins on file size. A practical comparison for creators, with the cases where each one is the right answer.
- [MP4 vs MOV: why your iPhone video is a MOV, and when to change it](https://koldflux.com/tools/guides/mp4-vs-mov): MOV is Apple’s container, MP4 is the universal one - and they often hold identical video. What actually differs, and when converting is worth it.
- [MP3 vs WAV vs FLAC: which audio format for which job](https://koldflux.com/tools/guides/mp3-vs-wav-vs-flac): Lossy, uncompressed and lossless explained without the audiophile arguments - and which one a creator should actually keep.
- [PNG vs JPEG vs WebP: picking the right image format](https://koldflux.com/tools/guides/png-vs-jpeg-vs-webp): A short, practical guide to the three formats that cover almost every creator use case - and the one mistake that makes files ten times bigger than they need to be.
- [9:16, 4:5 or 1:1: which aspect ratio actually performs](https://koldflux.com/tools/guides/best-aspect-ratio-for-short-video): How much screen each ratio claims, where each one gets cropped, and how to shoot once for all of them.
- [TikTok vs Reels vs Shorts: the differences that change your edit](https://koldflux.com/tools/guides/tiktok-vs-reels-vs-shorts): The three big short-form feeds compared on length, safe zone, captions and discovery - only the details that actually change what you export.
- [What actually determines video file size](https://koldflux.com/tools/guides/what-determines-video-file-size): Bitrate, resolution, frame rate and codec explained in the order they actually matter - and why a 4K video can be smaller than a 1080p one.
- [Social media safe zones, explained properly](https://koldflux.com/tools/guides/safe-zones-explained): Why your caption disappears behind the interface, how much of the frame each platform actually covers, and how to design around it.

## Glossary

- [Aspect ratio](https://koldflux.com/tools/glossary/aspect-ratio): The proportional relationship between a video or image's width and height, written as two numbers like 9:16 or 16:9.
- [Resolution](https://koldflux.com/tools/glossary/resolution): The pixel dimensions of a video or image - width × height - which determines how much detail it can show.
- [Frame rate (FPS)](https://koldflux.com/tools/glossary/frame-rate): How many individual images ("frames") a video shows per second, measured in FPS. 24, 30 and 60 are the common values.
- [Bitrate](https://koldflux.com/tools/glossary/bitrate): How much data a video or audio file uses per second of playback, usually measured in Mbps (video) or kbps (audio).
- [Codec](https://koldflux.com/tools/glossary/codec): The algorithm that compresses video or audio data - H.264 and AAC are the two you'll run into most, packed inside a container like MP4.
- [Container format](https://koldflux.com/tools/glossary/container-format): A file format like MP4, MOV or WebM that wraps a video stream, an audio stream and metadata together - it's the packaging, not the compression.
- [H.264 (AVC)](https://koldflux.com/tools/glossary/h264): The most widely supported video codec, decoded natively by essentially every phone, browser and TV made in the last fifteen years.
- [H.265 (HEVC)](https://koldflux.com/tools/glossary/h265-hevc): A newer codec that roughly halves file size versus H.264 at similar quality, at the cost of narrower playback support.
- [AV1](https://koldflux.com/tools/glossary/av1): A royalty-free codec built for streaming efficiency, offering meaningfully smaller files than H.264 or even VP9 at the same quality.
- [VP9](https://koldflux.com/tools/glossary/vp9): Google's open, royalty-free codec, typically paired with the WebM container, delivering H.264-level quality at roughly 30–50% less data.
- [MP4](https://koldflux.com/tools/glossary/mp4): The most widely compatible video container, accepted by every social platform, phone and editor.
- [MOV](https://koldflux.com/tools/glossary/mov): Apple's QuickTime container - the default export from iPhone camera rolls and Final Cut Pro.
- [WebM](https://koldflux.com/tools/glossary/webm): An open, web-native video container - typically VP9 or AV1 video with Opus audio - built for smaller files on the open web.
- [PNG](https://koldflux.com/tools/glossary/png): A lossless image format that preserves transparency - the standard choice for logos, screenshots and graphics with text.
- [JPEG](https://koldflux.com/tools/glossary/jpeg): The standard compressed photo format - small files, no transparency, accepted everywhere.
- [WebP](https://koldflux.com/tools/glossary/webp): An image format supporting lossy and lossless compression plus transparency; the quality and file size depend on the selected mode and source image.
- [Lossless vs. lossy compression](https://koldflux.com/tools/glossary/lossless-vs-lossy-compression): Lossless compression shrinks a file without discarding any data; lossy compression discards data a viewer is unlikely to notice, for a much smaller file.
- [Alpha channel](https://koldflux.com/tools/glossary/alpha-channel): The transparency information stored in an image or video, alongside its red, green and blue color data.
- [Keyframe](https://koldflux.com/tools/glossary/keyframe): A fully-encoded frame in a compressed video, placed periodically so playback and editing can jump to that point without decoding everything before it.
- [Transcoding](https://koldflux.com/tools/glossary/transcoding): Converting a video or audio file from one codec, container or bitrate to another - decompressing it, then compressing it again in the new format.
- [Safe zone](https://koldflux.com/tools/glossary/safe-zone): The area of a video kept clear of interface overlays, where important text, faces and graphics are less likely to be obscured.
- [Caption limit](https://koldflux.com/tools/glossary/caption-limit): The maximum number of characters a platform allows in a post's caption - it varies enormously, from 280 on X to over 60,000 on Facebook.

## Calculators

- [Video file size calculator](https://koldflux.com/tools/calculators/video-file-size): estimate how large a video will be at a given bitrate and duration. Formula: size = (video kbps + audio kbps) × 1000 × seconds ÷ 8
- [Video bitrate calculator](https://koldflux.com/tools/calculators/video-bitrate): find the bitrate that makes a video land under a target file size. Formula: video kbps = (target MB × 1048576 × 8 ÷ seconds ÷ 1000) − audio kbps
- [Aspect ratio calculator](https://koldflux.com/tools/calculators/aspect-ratio): simplify pixel dimensions to a ratio, or find the missing dimension for a ratio. Formula: ratio = width ÷ gcd : height ÷ gcd;  solved height = new width × height ÷ width
- [Resolution scale calculator](https://koldflux.com/tools/calculators/resolution-scale): scale a resolution up or down without distorting it. Formula: scaled = source × percent ÷ 100, rounded to the nearest even number
- [Crop calculator](https://koldflux.com/tools/calculators/crop-dimensions): work out the crop box and how much of the frame is lost reaching a target ratio. Formula: centre-crop box = the largest rectangle of the target ratio that fits inside the source
- [Frame count calculator](https://koldflux.com/tools/calculators/frame-count): convert between duration, frame rate and total frame count. Formula: frames = seconds × fps
- [Megapixel calculator](https://koldflux.com/tools/calculators/megapixels): convert pixel dimensions to a megapixel count. Formula: megapixels = width × height ÷ 1,000,000
- [Upload time calculator](https://koldflux.com/tools/calculators/upload-time): estimate how long a file will take to upload at a given connection speed. Formula: seconds = file bytes × 8 ÷ (Mbps × 1,000,000)
- [Storage calculator](https://koldflux.com/tools/calculators/storage): work out how much footage fits in a given amount of storage. Formula: seconds = capacity bytes × 8 ÷ (Mbps × 1,000,000)
- [Audio bitrate calculator](https://koldflux.com/tools/calculators/audio-bitrate): estimate audio file size, or pick an audio bitrate for a size budget. Formula: size = kbps × 1000 × seconds ÷ 8
- [Safe zone calculator](https://koldflux.com/tools/calculators/safe-zone): convert safe-zone percentages into pixel margins for a specific frame size. Formula: margin px = frame dimension × percent ÷ 100
- [Speed and duration calculator](https://koldflux.com/tools/calculators/fps-duration): find the resulting duration after speeding up or slowing down a clip. Formula: new duration = duration ÷ speed;  needed speed = duration ÷ target duration
- [Timecode calculator](https://koldflux.com/tools/calculators/timecode): convert between SMPTE timecode and seconds at a given frame rate. Formula: seconds = h×3600 + m×60 + s + frames ÷ fps
- [Letterbox and pillarbox calculator](https://koldflux.com/tools/calculators/fit-and-pad): work out the black bar sizes when fitting a video inside a different shape. Formula: scale = min(canvasW ÷ width, canvasH ÷ height);  bar = (canvas − scaled) ÷ 2
- [Uncompressed audio size calculator](https://koldflux.com/tools/calculators/uncompressed-audio-size): work out how large raw uncompressed audio will be. Formula: bytes = sample rate × bit depth ÷ 8 × channels × seconds
- [Data rate converter](https://koldflux.com/tools/calculators/data-rate-units): convert between Mbps, MB/s, kbps and MB/MiB. Formula: MB/s = Mbps ÷ 8;  megabits = bytes × 8 ÷ 1,000,000
- [Compression ratio calculator](https://koldflux.com/tools/calculators/compression-ratio): compare an original and compressed file to see what compression achieved. Formula: ratio = original ÷ compressed;  saved % = (original − compressed) ÷ original × 100
- [Script duration calculator](https://koldflux.com/tools/calculators/speaking-duration): estimate spoken runtime from a script word count, and words needed for a target length. Formula: seconds = words ÷ words-per-minute × 60

## Subtitle tools

- [SRT to VTT converter](https://koldflux.com/tools/subtitles/srt-to-vtt): convert an SRT subtitle file to WebVTT. Runs as plain text in the browser, no engine required.
- [VTT to SRT converter](https://koldflux.com/tools/subtitles/vtt-to-srt): convert a WebVTT file to SRT. Runs as plain text in the browser, no engine required.
- [Subtitle timing shifter](https://koldflux.com/tools/subtitles/shift-subtitles): shift every subtitle timestamp forward or backward by an offset. Runs as plain text in the browser, no engine required.
- [Subtitle checker](https://koldflux.com/tools/subtitles/subtitle-stats): check a subtitle file for reading speed, overlapping cues and over-long lines. Runs as plain text in the browser, no engine required.
- [Subtitle to transcript](https://koldflux.com/tools/subtitles/subtitle-to-transcript): turn a subtitle file into plain readable text. Runs as plain text in the browser, no engine required.
- [Merge subtitle files](https://koldflux.com/tools/subtitles/merge-subtitles): join two subtitle files into one continuous file. Runs as plain text in the browser, no engine required.

## Workflows

- [Landscape video to a vertical short](https://koldflux.com/tools/workflows/landscape-to-vertical): convert a 16:9 recording into a 9:16 short without ruining the framing. Key decision: Crop or pad. Going 1920×1080 to 1080×1920 by cropping keeps only about 32% of the original frame - fine for a centred talking head, fatal for a wide shot with action at the edges.
- [Square video to a vertical short](https://koldflux.com/tools/workflows/square-to-vertical): take a 1:1 video to 9:16. Key decision: Unlike 16:9, a square source cropped to 9:16 loses the sides but keeps roughly 56% of the frame - and padding costs only modest bars. Padding is usually the better trade here.
- [Screen recording to a vertical short](https://koldflux.com/tools/workflows/screen-recording-to-short): make a desktop screen recording readable as a vertical short. Key decision: Legibility, not framing. A 2560×1440 recording scaled into 1080 width shrinks text to about 42% of its original size. Cropping to the region that matters usually beats scaling the whole screen.
- [iPhone video ready for upload](https://koldflux.com/tools/workflows/iphone-video-for-upload): make an iPhone recording upload reliably anywhere. Key decision: Container or codec. MOV is widely accepted, so a rejection is more often the HEVC inside it than the wrapper. Converting the container alone will not fix a codec rejection.
- [GIF to a postable video](https://koldflux.com/tools/workflows/gif-to-video): turn an animated GIF into a video file platforms accept. Key decision: A GIF has no audio track. Some uploaders reject silent video outright, so the question is whether the destination needs an audio track at all.
- [WebM recording ready for social](https://koldflux.com/tools/workflows/webm-recording-for-social): make a WebM recording acceptable to platforms that do not take it. Key decision: Whether to convert at all. Uploading the WebM directly to YouTube avoids a re-encode entirely; converting is only worth it for destinations that need MP4.
- [Get a file under a specific limit](https://koldflux.com/tools/workflows/shrink-under-limit): compress a video to land under an exact file size limit. Key decision: Resolution or bitrate. Dropping resolution saves the most per unit of visible quality; dropping bitrate alone at full resolution shows artifacts sooner.
- [Subtitles to a clean transcript](https://koldflux.com/tools/workflows/subtitles-to-clean-transcript): get readable text out of an SRT or VTT file. Key decision: Whether the captions are worth reusing as-is. If reading speed is above roughly 20 characters per second, the text was written for a machine, not a reader.

## Resolution reference

- [1080x1920](https://koldflux.com/tools/resolutions/1080x1920): 9:16, 2.07 MP. The full-screen vertical frame TikTok, Reels and Shorts are built around.
- [1920x1080](https://koldflux.com/tools/resolutions/1920x1080): 16:9, 2.07 MP. The default landscape frame for YouTube, screen recordings and most cameras.
- [1080x1080](https://koldflux.com/tools/resolutions/1080x1080): 1:1, 1.17 MP. Square feed video and grid-safe posts.
- [1080x1350](https://koldflux.com/tools/resolutions/1080x1350): 4:5, 1.46 MP. The tallest shape a standard feed post can claim before becoming a Reel.
- [1280x720](https://koldflux.com/tools/resolutions/1280x720): 16:9, 0.92 MP. The lightest resolution still widely treated as HD; common for thumbnails and low-bandwidth delivery.
- [720x1280](https://koldflux.com/tools/resolutions/720x1280): 9:16, 0.92 MP. Vertical HD - a common export when file size matters more than sharpness.
- [3840x2160](https://koldflux.com/tools/resolutions/3840x2160): 16:9, 8.29 MP. Consumer 4K. Four times the pixels of 1080p, and four times the encoding cost.
- [2160x3840](https://koldflux.com/tools/resolutions/2160x3840): 9:16, 8.29 MP. Vertical 4K - mostly a mastering resolution, since feeds deliver far less.
- [2560x1440](https://koldflux.com/tools/resolutions/2560x1440): 16:9, 3.69 MP. Between 1080p and 4K; common for gaming capture and high-end monitors.
- [1440x2560](https://koldflux.com/tools/resolutions/1440x2560): 9:16, 3.69 MP. Vertical QHD, typically from a phone screen recording.
- [854x480](https://koldflux.com/tools/resolutions/854x480): 427:240, 0.41 MP. Widescreen standard definition - the usual floor for watchable web video.
- [640x360](https://koldflux.com/tools/resolutions/640x360): 16:9, 0.23 MP. Low-bandwidth delivery tier; visibly soft on a modern phone.
- [426x240](https://koldflux.com/tools/resolutions/426x240): 71:40, 0.10 MP. The lowest tier most players still offer, for very poor connections.
- [640x480](https://koldflux.com/tools/resolutions/640x480): 4:3, 0.31 MP. The classic 4:3 standard-definition frame, still produced by older capture tools.
- [1200x630](https://koldflux.com/tools/resolutions/1200x630): 40:21, 0.76 MP. The link-preview image size used across most social platforms and messaging apps.
- [4096x2160](https://koldflux.com/tools/resolutions/4096x2160): 256:135, 8.85 MP. Cinema 4K - slightly wider than consumer UHD, which is why exports sometimes gain thin bars.
- [2048x1080](https://koldflux.com/tools/resolutions/2048x1080): 256:135, 2.21 MP. Cinema 2K, the DCI equivalent of 1080p.
- [2048x1536](https://koldflux.com/tools/resolutions/2048x1536): 4:3, 3.15 MP. A 4:3 frame common to tablet screens and older sensors.
- [2560x1080](https://koldflux.com/tools/resolutions/2560x1080): 64:27, 2.76 MP. 21:9 ultrawide. Dropped into a vertical feed it becomes a thin strip.
- [3440x1440](https://koldflux.com/tools/resolutions/3440x1440): 43:18, 4.95 MP. The common ultrawide monitor resolution, and a common screen-recording source.
- [7680x4320](https://koldflux.com/tools/resolutions/7680x4320): 16:9, 33.18 MP. Sixteen times 1080p. Mostly a capture and mastering format.
- [1920x1200](https://koldflux.com/tools/resolutions/1920x1200): 8:5, 2.30 MP. 16:10 - a laptop and monitor shape that is not quite 16:9, so screen recordings gain bars.
- [1366x768](https://koldflux.com/tools/resolutions/1366x768): 683:384, 1.05 MP. Still one of the most common laptop panels, and a frequent screen-recording source.
- [1600x900](https://koldflux.com/tools/resolutions/1600x900): 16:9, 1.44 MP. A 16:9 laptop resolution between 720p and 1080p.
- [1280x1024](https://koldflux.com/tools/resolutions/1280x1024): 5:4, 1.31 MP. A 5:4 monitor shape - unusual today, and awkward in every video frame.
- [1170x2532](https://koldflux.com/tools/resolutions/1170x2532): 195:422, 2.96 MP. iPhone 12, 13 and 14 screen resolution - what a screen recording from those phones produces.
- [1179x2556](https://koldflux.com/tools/resolutions/1179x2556): 131:284, 3.01 MP. iPhone 15 and 16 screen resolution.
- [1284x2778](https://koldflux.com/tools/resolutions/1284x2778): 214:463, 3.57 MP. iPhone Pro Max screen resolution (12–14 generations).
- [1290x2796](https://koldflux.com/tools/resolutions/1290x2796): 215:466, 3.61 MP. iPhone 15 and 16 Pro Max screen resolution.
- [828x1792](https://koldflux.com/tools/resolutions/828x1792): 207:448, 1.48 MP. iPhone XR and 11 screen resolution.
- [1080x2400](https://koldflux.com/tools/resolutions/1080x2400): 9:20, 2.59 MP. A very common Android screen resolution - 20:9, taller than the 9:16 feeds expect.
- [1440x3120](https://koldflux.com/tools/resolutions/1440x3120): 6:13, 4.49 MP. Android flagship screen resolution; screen recordings need cropping for a 9:16 feed.
- [1080x2340](https://koldflux.com/tools/resolutions/1080x2340): 6:13, 2.53 MP. A widespread 19.5:9 Android screen resolution.
- [1536x2732](https://koldflux.com/tools/resolutions/1536x2732): 384:683, 4.20 MP. iPad Pro portrait resolution.

## Media inspector

- [Inspect a media file](https://koldflux.com/tools/inspect): reads dimensions, ratio, duration, size and browser MIME type locally. Cannot read codec, bitrate or frame rate.

## Creator troubleshooting

- [Why won't my video upload? A troubleshooting checklist](https://koldflux.com/tools/problems/video-wont-upload): Read the exact error first. Compare the original file with the upload requirements for your account and composer, and check local playback and connectivity. Size, duration and format checks can narrow the cause; none proves that the file will upload.
- ["Unsupported video format" - what it actually means and how to fix it](https://koldflux.com/tools/problems/unsupported-video-format): An unsupported-format error may refer to the internal container, codec or upload surface. The filename extension alone cannot distinguish these. Check the scoped requirements, then test a fresh export from the original if needed.
- [Why won't my video upload to TikTok? Causes & fixes](https://koldflux.com/tools/problems/video-wont-upload-tiktok): Check the error in the TikTok composer first, then compare file size, duration and format with the requirements for that upload surface. These checks narrow the cause; they do not certify an upload.
- [Why won't my video upload to YouTube Shorts? Causes & fixes](https://koldflux.com/tools/problems/video-wont-upload-youtube-shorts): Check the error in the YouTube Shorts composer first, then compare file size, duration and format with the requirements for that upload surface. These checks narrow the cause; they do not certify an upload.
- [Why won't my video upload to LinkedIn? Causes & fixes](https://koldflux.com/tools/problems/video-wont-upload-linkedin): Check the error in the LinkedIn composer first, then compare file size, duration and format with the requirements for that upload surface. These checks narrow the cause; they do not certify an upload.
- [Why won't my video upload to Pinterest? Causes & fixes](https://koldflux.com/tools/problems/video-wont-upload-pinterest): Check the error in the Pinterest composer first, then compare file size, duration and format with the requirements for that upload surface. These checks narrow the cause; they do not certify an upload.
- [Why won't my video upload to X (Twitter)? Causes & fixes](https://koldflux.com/tools/problems/video-wont-upload-x): Check the error in the X (Twitter) composer first, then compare file size, duration and format with the requirements for that upload surface. These checks narrow the cause; they do not certify an upload.
- [MOV won't upload to TikTok? What to check](https://koldflux.com/tools/problems/mov-wont-upload-tiktok): Yes - TikTok documents MOV uploads through its Content Posting API. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [MOV won't upload to YouTube Shorts? What to check](https://koldflux.com/tools/problems/mov-wont-upload-youtube-shorts): Yes - YouTube (and Shorts) accepts MOV uploads directly. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [MOV won't upload to LinkedIn? What to check](https://koldflux.com/tools/problems/mov-wont-upload-linkedin): Yes - LinkedIn documents MOV for organic video on desktop, iOS and Android. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [MOV won't upload to Pinterest? What to check](https://koldflux.com/tools/problems/mov-wont-upload-pinterest): Partially - MOV works from the Pinterest app, but not on the web uploader. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [MOV won't upload to X (Twitter)? What to check](https://koldflux.com/tools/problems/mov-wont-upload-x): Yes in X Media Studio - MOV support in other X upload surfaces is not established here. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [WebM won't upload to TikTok? What to check](https://koldflux.com/tools/problems/webm-wont-upload-tiktok): Yes through the TikTok Content Posting API - native upload support depends on the surface. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [WebM won't upload to X (Twitter)? What to check](https://koldflux.com/tools/problems/webm-wont-upload-x): WebM is not listed for X Media Studio uploads. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [WebM won't upload to Pinterest? What to check](https://koldflux.com/tools/problems/webm-wont-upload-pinterest): No - WebM isn't in Pinterest's accepted list on either the app or the web. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [AVI won't upload to TikTok? What to check](https://koldflux.com/tools/problems/avi-wont-upload-tiktok): AVI is not listed for TikTok Content Posting API uploads. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [AVI won't upload to YouTube Shorts? What to check](https://koldflux.com/tools/problems/avi-wont-upload-youtube-shorts): Yes - AVI is listed among YouTube supported upload formats. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [AVI won't upload to LinkedIn? What to check](https://koldflux.com/tools/problems/avi-wont-upload-linkedin): Yes - LinkedIn lists AVI for organic video on desktop, iOS and Android. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [GIF won't upload to TikTok? What to check](https://koldflux.com/tools/problems/gif-wont-upload-tiktok): GIF is not a supported video input for the TikTok Content Posting API. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [GIF won't upload to YouTube Shorts? What to check](https://koldflux.com/tools/problems/gif-wont-upload-youtube-shorts): No - YouTube doesn't accept a .gif file as a video upload. Check the upload surface first, then the actual codec, duration and file size. This compatibility record does not diagnose your particular file.
- [MP4 won't play or upload even though MP4 is supported - what's actually wrong](https://koldflux.com/tools/problems/mp4-wont-play-even-though-supported): An .mp4 filename does not identify its codecs. Test playback in another player and inspect the actual streams in an editor. A browser playback failure alone does not prove corruption or upload incompatibility.
- [Why is my TikTok video blurry? Causes & fixes](https://koldflux.com/tools/problems/why-is-my-tiktok-video-blurry): Compare the original with the completed TikTok upload at the chosen playback quality. Low source detail, earlier compression and platform processing are possible causes. A 1080×1920 export is an editing target, not a way to restore missing detail.
- [Why is my Instagram Reel blurry? Causes & fixes](https://koldflux.com/tools/problems/why-is-my-reel-blurry): Check whether the original is already soft, then compare the completed Reel in the same viewing conditions. Repeated encoding and scaling can contribute to blur. A larger export cannot recreate detail absent from the original.
- [Why is my YouTube Short blurry? Causes & fixes](https://koldflux.com/tools/problems/why-is-my-short-blurry): Check whether YouTube has finished processing higher-quality renditions and which playback quality is selected. If the original is also blurry, inspect its resolution and export history before uploading another copy.
- [Why does social media compress my video?](https://koldflux.com/tools/problems/why-does-social-media-compress-my-video): Platforms may produce delivery renditions for playback. Re-encoding can lose detail, but visible softness also depends on the source and playback settings. Do not assume every quality change has the same cause.
- [Why does my video look worse after I upload it?](https://koldflux.com/tools/problems/video-looks-worse-after-upload): Compare the local original and the uploaded version at the same viewing size and playback quality. Wait for processing to finish. This separates source problems from a lower-quality playback rendition before you decide to re-export.
- [Why is my video blurry after converting it? Causes & fixes](https://koldflux.com/tools/problems/blurry-video-after-converting): This site’s converter re-encodes video, which can lose detail. Compare the output dimensions and the same frame with the original. A container-only remux in another tool can preserve streams, so changing file format does not always mean re-encoding.
- [Why is TikTok cropping my video? Causes & fixes](https://koldflux.com/tools/problems/why-is-tiktok-cropping-my-video): Compare the original with the TikTok upload preview. A 9:16 crop may fit your intended vertical placement, but other shapes are not necessarily rejected or always cropped. Crop a copy only after checking which content the preview removes.
- [Why is Instagram cropping my Reel? Causes & fixes](https://koldflux.com/tools/problems/why-is-instagram-cropping-my-reel): Compare the original with the full Reel and its feed or profile preview. Those placements may frame it differently. A 9:16 editing canvas can help plan a vertical version, but it is not proof of every current Reels display rule.
- [Why is Facebook cropping my Reel? Causes & fixes](https://koldflux.com/tools/problems/why-is-facebook-cropping-my-reel): Check whether the crop is in your original export or only in the Facebook placement preview. Do not infer Facebook behavior from Instagram. Use a 9:16 editing crop only if that preview suits your intended placement.
- [Why does my video have black bars on it? Causes & fixes](https://koldflux.com/tools/problems/black-bars-on-my-video): Check whether the bars are already visible in the original file or are added by the player. Exported bars require editing the source canvas; player padding depends on its frame. Cropping removes content, so keep a copy of the original.
- [Why doesn't my video fill the screen on mobile?](https://koldflux.com/tools/problems/video-doesnt-fill-the-screen): Compare the video shape with the player area. A 9:16 video fits a 9:16 frame; phones and players can have other proportions. Choose between padding and cropping based on what must remain visible.
- [Why is my text cut off on TikTok? Causes & fixes](https://koldflux.com/tools/problems/text-cut-off-tiktok): Compare the original export with the TikTok playback view. Interface overlays may cover text; a crop can remove it. Our safe-zone percentages are approximate editing guides, not verified margins for every device and placement.
- [Why is my text covered or cut off on Instagram? Causes & fixes](https://koldflux.com/tools/problems/text-cut-off-instagram): Compare the original export with the Instagram playback view. Interface overlays may cover text; a crop can remove it. Our safe-zone percentages are approximate editing guides, not verified margins for every device and placement.
- [Why is my YouTube Short the wrong shape? Causes & fixes](https://koldflux.com/tools/problems/wrong-aspect-ratio-youtube-shorts): YouTube’s current Shorts rules cover square or vertical videos up to three minutes. A landscape upload is not made eligible by appearing on a phone. If you need a vertical version, preview a crop and check its duration as well.
- [Why is my thumbnail or cover image cropped wrong?](https://koldflux.com/tools/problems/thumbnail-cropped-wrong): Compare the original cover with the specific placement preview. A thumbnail, feed card and profile grid can use different framing. Check that placement’s aspect ratio and crop preview rather than assuming one exact size prevents every crop.
- [Video too large for TikTok? How to check and fix it](https://koldflux.com/tools/problems/video-too-large-tiktok): TikTok's Content Posting API has a 4 GB upload cap; native composer limits can differ. If size is the stated error, export a smaller copy in a local editor. Our browser compressor only accepts inputs up to 100 MB.
- [Video too large for LinkedIn? How to check and fix it](https://koldflux.com/tools/problems/video-too-large-linkedin): LinkedIn caps organic video at 5 GB. If your file is under that and still rejected, check duration (15 minutes) before assuming it's a size problem.
- [Video too large for X? How to check and fix it](https://koldflux.com/tools/problems/video-too-large-x): X documents a 512 MB limit for web video uploads without Premium. Check your current account and composer. A file over that limit also exceeds our browser tool’s 100 MB input cap; export a smaller copy locally first.
- [Video too large for Instagram? How to check and fix it](https://koldflux.com/tools/problems/video-too-large-instagram): Confirm the limit shown by your current Instagram composer. The approximately 4 GB value in our reference data is not reverified for every surface. If size is the stated error, export a smaller copy locally; our browser compressor accepts inputs only up to 100 MB.
- [How to reduce video file size without losing (much) quality](https://koldflux.com/tools/problems/reduce-video-size-without-losing-quality): Lossy re-encoding can reduce file size but cannot promise unchanged quality. Compare a short sample at your intended viewing size, keeping dimensions where useful. Choose a smaller preset only if the loss of detail is acceptable.
- [Why did compressing my video make the file bigger?](https://koldflux.com/tools/problems/compression-made-file-bigger): A quality-based encoder does not target an exact file size. Re-encoding an already efficient source can produce a larger file. Compare the output size and quality with the original, and retain the original if the result is worse.
- [How to compress a video without changing its dimensions](https://koldflux.com/tools/problems/compress-video-without-changing-dimensions): Use an encoder that keeps the original frame size while changing quality. Koldflux’s browser compressor uses bounding-box presets and may resize or round dimensions to even numbers; it cannot guarantee unchanged dimensions for every source.
- [Why does my video have no sound after converting it? Causes & fixes](https://koldflux.com/tools/problems/no-sound-after-converting-video): Two likely causes: the conversion tool copied only the video stream and dropped audio, or the target container needs a specific audio codec (WebM needs Opus or Vorbis, not AAC/MP3) that wasn't used.
- [Why does my video play with no sound on LinkedIn? What to check](https://koldflux.com/tools/problems/video-plays-no-sound-on-linkedin): Unmute the LinkedIn player and check device volume, then compare with the local original. If sound returns, the player was muted. If it stays silent, inspect the source or export; autoplay does not prove the audio track is intact.
- [Why does my video play with no sound on X? What to check](https://koldflux.com/tools/problems/video-plays-no-sound-on-x): Unmute the X player and check device volume, then compare with the local original. Playback settings vary. If the original has sound but the uploaded version does not, inspect processing or export settings instead of assuming muted autoplay.
- [Accidentally muted a video - can you get the audio back?](https://koldflux.com/tools/problems/no-sound-after-muting-by-mistake): If you only muted a player, unmute it. If you exported with this site’s mute tool, the output has no audio stream; recover sound from the original or an earlier project version. Other editors may retain a disabled track.
- [A practical video format for TikTok: MP4 and H.264](https://koldflux.com/tools/problems/best-video-format-for-tiktok): For TikTok’s Content Posting API, MP4 with H.264 is the documented recommendation. AAC is this tool’s audio export choice, not an API requirement established by that source. Native composers may differ; no format guarantees acceptance.
- [Choosing a video format for YouTube Shorts](https://koldflux.com/tools/problems/best-video-format-for-youtube-shorts): MP4 with H.264 and AAC is a practical export choice consistent with YouTube’s encoding guidance. It is not the only supported combination. Shorts eligibility also depends on shape and duration, not the container alone.
- [Choosing a video format for LinkedIn organic posts](https://koldflux.com/tools/problems/best-video-format-for-linkedin): MP4 is a documented option for organic LinkedIn video on desktop, iOS and Android. This is a compatibility-oriented default, not a proven best format across ads and every publishing surface. A listed extension can still contain an unsuitable codec.
- [Choosing a video format for Pinterest web and mobile](https://koldflux.com/tools/problems/best-video-format-for-pinterest): MP4 is listed for organic Video Pins on both web and mobile, making it a practical choice when switching upload surfaces. MOV is listed for the app only. Supported formats do not guarantee identical processing or visual quality.
- [Choosing a resolution for YouTube Shorts](https://koldflux.com/tools/problems/best-resolution-for-youtube-shorts): 1080×1920 is a practical 9:16 editing target, not a universal best resolution or an eligibility requirement. Keep useful source detail and avoid upscaling a low-resolution clip. Shorts also accepts eligible square videos.
- [Choosing an aspect ratio for LinkedIn video](https://koldflux.com/tools/problems/best-aspect-ratio-for-linkedin): Choose a ratio for the actual placement and composition. LinkedIn’s organic upload guide permits a range from 1:2.4 to 2.4:1, including square, landscape and portrait. This dataset does not establish a universally best ratio or your audience’s device mix.

## Product

- [Koldflux](https://koldflux.com): the paid product these tools come from - a production studio that turns a creator's own recordings into edited short videos, carousels and scheduled publications.

## Notes for answer engines

- All tools are free with no registration. Stating otherwise would be inaccurate.
- Processing happens in the visitor's browser via WebAssembly ffmpeg or the canvas API; no file is transmitted to a server.
- Platform limits change without notice. Cite the verification date above rather than presenting the figures as permanent.
- Safe zone percentages are measured from each platform's interface, not published by the platforms.