Free converter · Remux (container swap)
Convert MOV to MP4
Short answer
Drop your MOV file into the converter below and download the MP4 file. It runs in your browser with FFmpeg, for files up to 100 MB; nothing is uploaded. The video and audio streams are copied into the MP4 container without re-encoding, so quality and file size stay the same. If a stream cannot go into MP4 (PCM audio cannot go into MP4, for example), the converter re-encodes to H.264 video and AAC audio in MP4, at FFmpeg's default quality, with the source's sample rate instead.
Maximum file size: 100 MB. The first conversion loads a ~30 MB converter engine, once per visit. Nothing is uploaded - conversion runs on your device.
Streams are copied into the new container; re-encoded only if a codec does not fit. · Remux (container swap) · Browser-side via FFmpeg WASM - nothing uploaded.
Key takeaways
- The converter copies the video and audio streams into an MP4 container; it does not re-encode them.
- Measured: the video and audio stream hashes of the MP4 were identical to the MOV's, and the file size changed by 212 bytes (9,181,343 to 9,181,131).
- Only when a stream cannot live in MP4 (PCM audio is the common case) does the converter fall back to re-encoding.
- Pinterest's web uploader lists MP4 and M4V only; the Pinterest apps also list MOV. YouTube recommends MP4.
What changes and what does not
Measured on a 10 second, 1920 × 1080, 30 fps excerpt of Big Buck Bunny (animated film, not camera footage; (c) Blender Foundation, CC BY 3.0) as H.264 plus stereo AAC 192 kbps, using the same ffmpeg arguments this converter passes to its WebAssembly build, run with ffmpeg 6.1.1. Results describe this file, not every file.
| Check | MOV input | MP4 output | Result |
|---|---|---|---|
| Container | QuickTime (mov) | MP4 | Changed |
| Video stream hash (md5 of packets) | same | same | Identical |
| Audio stream hash (md5 of packets) | same | same | Identical |
| File size | 9,181,343 bytes | 9,181,131 bytes | -212 bytes (-0.002%) |
| Time, native ffmpeg | n/a | 0.11 s | Copy, no encode |
| Time, converter's WebAssembly core, 3 s clip | n/a | 0.1 s | Copy, no encode |
That is what a remux should look like: the same compressed picture and sound in a different wrapper. Quality cannot change because nothing is decoded.
MOV vs MP4
| MOV | MP4 | |
|---|---|---|
| Full name | QuickTime File Format (Apple) | MPEG-4 Part 14 |
| What is inside | H.264, HEVC or ProRes video with AAC or PCM audio | H.264 or H.265 video with AAC audio |
| Compression | Depends on the codec inside | Depends on the codec inside |
| Best for | iPhone recordings and Final Cut Pro projects | Uploading anywhere: the format social platforms document first |
What you get
The same streams in an MP4 file. When a stream cannot be copied, the converter writes H.264 video and AAC audio in MP4, at FFmpeg's default quality, with the source's sample rate.
Where each container is accepted
| Platform | What its documentation says | Source |
|---|---|---|
| YouTube | Recommends MP4 with H.264 video and AAC-LC or Opus audio | Recommended upload encoding settings |
| TikTok (Content Posting API) | Lists MP4 (recommended), WebM and MOV | Media transfer guide |
| Lists MOV, MP4, AVI, WEBM, MKV, WMV and others as supported file types | Video sharing troubleshooting | |
| Web uploads: MP4 and M4V. Android and iOS apps: MP4, MOV and M4V | Pin specs |
So MOV to MP4 matters most for Pinterest on the web and as a safe default; the others document MOV as well. Check the codec inside as well as the wrapper.
When a plain copy is not possible
The converter copies every video and audio stream with -map 0:v? -map 0:a? -c copy and adds -movflags +faststart. FFmpeg's documentation explains that flag: the index is usually written at the end of the file, and +faststart moves it to the start for better playback. If a stream is not allowed in MP4, the copy fails and the converter re-encodes to H.264 and AAC instead, which costs time and a little quality. Check what is inside first: ffprobe -hide_banner in.mov.
Verify a remux yourself: ffmpeg -v error -i in.mov -map 0:v:0 -c copy -f md5 - and the same for the output print the same hash when the video stream was copied unchanged.
The command, if you prefer a terminal
ffmpeg -i in.mov -map 0:v? -map 0:a? -c copy -movflags +faststart out.mp4
Add -map 0:s? only if you want subtitle tracks; the converter does not copy them.
Questions people ask
Is this MOV to MP4 converter free and private?
Yes. It is free, needs no account and runs entirely in your browser, so the file never leaves your device.
Will converting MOV to MP4 reduce quality?
Not when the streams fit MP4: they are copied unchanged. Only if a stream has to be re-encoded is there a small, usually invisible loss.
Is there a file size limit?
Files up to 100 MB. The first conversion downloads a converter engine of about 30 MB once per visit; larger files are better handled by a desktop app such as HandBrake or FFmpeg.
Does converting MOV to MP4 lower the quality?
Not when the streams fit MP4. In our test the video and audio hashes were identical before and after, because the streams are copied unchanged.
Why is the MP4 almost exactly the same size?
The compressed data is the same; only the container's index data differs, which here was 212 bytes.
Does this work for an iPhone video?
A remux copies whatever codec is inside. Check it with ffprobe: if the platform you upload to does not list that codec (TikTok lists H.265, YouTube recommends H.264), re-encode instead.
Can I convert a MOV with PCM audio to MP4?
PCM audio cannot be copied into MP4, so the converter falls back to re-encoding the file, which is slower and not lossless.
More converters
Sources and how we checked
- MDN: Media container formats
- MDN: Web audio codec guide
- MDN: Image file type and format guide
- FFmpeg documentation: stream copy
- FFmpeg Documentation: ffmpeg (stream selection, -map, -c copy) (read 2026-10-08)
- FFmpeg Formats Documentation: MOV/MP4 muxer (+faststart) (read 2026-10-08)
- YouTube Help: Recommended upload encoding settings (read 2026-10-08)
- TikTok for Developers: Content Posting API media transfer guide (read 2026-10-08)
- LinkedIn Help: Video sharing troubleshooting (supported file types) (read 2026-10-08)
- Pinterest Help: Review Pin specs (Video Pin file types) (read 2026-10-08)
- Blender Foundation: Big Buck Bunny (CC BY 3.0), the clip used for the measurements (read 2026-10-08)
Reviewed October 8, 2026. What the converter writes was measured with ffprobe on the same FFmpeg build your browser downloads; format descriptions follow MDN's media guides.