Free tool · H.264 · Runs in your browser
Rotate a video
Short answer
Pick 90° clockwise, 180° or 90° counter-clockwise and the tool turns every frame and re-encodes the result as H.264 inside your browser. On our 10 second 1920 × 1080 test clip a 90° turn gave a 1080 × 1920 file of 2.62 MB in 36 s, with SSIM 0.9835 against the correctly rotated source. Nothing is uploaded.
Batch is free and unlimited - files are processed one after another on your device, with no queue or daily cap. Maximum 100 MB per file; the first run loads a ~30 MB engine once per visit.
Key takeaways
- Rotation swaps width and height for quarter turns: the 1920 × 1080 clip became 1080 × 1920 at 90° and 270°, and stayed 1920 × 1080 at 180°.
- The picture is re-encoded, not just flagged. Against the source rotated the same way, SSIM was 0.9835, 0.9836 and 0.9835. The three outputs were 2.62 MB, 2.64 MB and 2.62 MB, against 13.53 MB for the source.
- The time for a 10 second 1080p clip was 36 s to 36 s, about 3.6 times its length, because every frame is decoded and encoded again.
- A phone clip that stores its rotation as metadata is handled by ffmpeg before the turn: our test file stored 1920 × 1080 with a 90 degree flag, and the result was 1920 × 1080. Check the preview if the file looked right in your player.
- Clockwise is transpose=1 and counter-clockwise is transpose=2 in FFmpeg's documentation; 180° is a horizontal and a vertical flip. The audio is kept and re-encoded as AAC.
What the tool does to your file
A quarter turn cannot be done by copying the compressed picture, so the tool decodes each frame, turns it and encodes it again. The sound is re-encoded alongside.
| Choice | Filter | Result for a 1920 × 1080 source |
|---|---|---|
| 90° clockwise | transpose=1 | 1080 × 1920 |
| 180° | hflip,vflip | 1920 × 1080 |
| 90° counter-clockwise | transpose=2 | 1080 × 1920 |
Video is written as H.264 (libx264) with the veryfast preset and yuv420p, at the encoder default quality of CRF 23. FFmpeg's documentation defines the transpose directions: 1 rotates 90 degrees clockwise and 2 rotates 90 degrees counterclockwise.
Measured: all three rotations
Measured on a 10 second 1920 × 1080 excerpt of Big Buck Bunny (CC BY 3.0, Blender Foundation) with a speech soundtrack. It is an animated film, not camera footage, so the sizes of camera video will differ. The tool's own ffmpeg arguments ran on the same single-thread WebAssembly engine your browser downloads; times are from a headless run and your device will differ.
SSIM compares each output with the source turned by the same filter; 1.0 would be identical.
| Rotation | Output frame | Output size | Video bitrate | SSIM | Time |
|---|---|---|---|---|---|
| 90° clockwise | 1080 × 1920 | 2,618,388 bytes (2.62 MB) | 2,093 kbps | 0.9835 | 35.6 s |
| 90° counter-clockwise | 1080 × 1920 | 2,639,239 bytes (2.64 MB) | 2,110 kbps | 0.9836 | 36.0 s |
| 180° | 1920 × 1080 | 2,624,242 bytes (2.62 MB) | 2,098 kbps | 0.9835 | 36.0 s |
The Rotate a video tool on a 10 second 1080p clip, 13.53 MB as published.
The files are far smaller than the 13.53 MB source because the encoder aims at a fixed quality, not at the source's 10,827 kbps. A source that is already small can come out larger.
Why a rotated file can look right in one player and wrong in another
Phones often record a landscape frame and add a flag that says "show this turned 90 degrees". Players that read the flag show the video upright; others show it sideways. ffmpeg applies that flag when it decodes, so the tool turns the picture you would see in a player that honors it. Our test file stored 1920 × 1080 pixels with a 90 degree flag and a 90° turn produced 1920 × 1080.
If the preview in the tool is already upright, do not rotate. If it is sideways, pick the direction that fixes it.
What it costs
- Time: about 3.6 seconds per second of 1080p video in our run. Shorter or smaller clips are proportionally quicker.
- Quality: one re-encode. Rotate your original once rather than a copy that was already rotated.
- Size: set by the quality target, not by the source.
Free tools:Crop a video preciselyTrim by timestampCompress a videoCrop video to 9:16
Questions people ask
How do I rotate a video 90 degrees?
Choose 90° clockwise or 90° counter-clockwise, pick your file and run it. The result downloads as an MP4.
Does rotating reduce the quality?
The picture is re-encoded once: SSIM 0.9835 against the correctly rotated source on our clip.
Why does it take so long?
Every frame is decoded, turned and encoded again. A 10 second 1080p clip took 36 s in a headless run of the same engine.
Why did my video change shape?
A quarter turn swaps width and height. Our 1920 × 1080 clip became 1080 × 1920.
My video plays sideways only on one device. What do I do?
It probably carries a rotation flag that some players ignore. Rotate it with the tool and check the result in the player that shows it wrong.
Is the sound kept?
Yes, re-encoded as AAC.
Is anything uploaded?
No. Files up to 100 MB are processed in your browser.
Related
Sources and how we checked
- FFmpeg Filters Documentation (read 2026-10-06)
- FFmpeg wiki: Encode/H.264 (CRF and presets) (read 2026-10-06)
Reviewed October 9, 2026. The measurements ran the tool’s own ffmpeg arguments on the same single-thread WebAssembly engine your browser downloads. The script, the results and the saved documentation are in data/seo/hub/evidence/2026-10-09/tools.