Free converter · Lossy re-encode
Convert WebM to MOV
Short answer
Drop your WebM file into the converter below and download the MOV file. It runs in your browser with FFmpeg, for files up to 100 MB; nothing is uploaded. The file is re-encoded to H.264 video and AAC audio in a QuickTime MOV. Re-encoding takes longer than a container swap and costs some quality; how much depends on the clip and on the quality setting, and at the converter's default setting the loss can be visible, so keep the original.
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.
VP8/Opus re-encoded to H.264/AAC inside MOV. · Lossy re-encode · Browser-side via FFmpeg WASM - nothing uploaded.
Key takeaways
- The 2.11 MB WebM file was re-encoded and became 3.20 MB (+51.9%).
- The result holds: Video: h264 1920x1080; Audio: aac 48000 Hz 2 ch.
- In your browser the same conversion of a 3 second clip took 31.7 seconds on the single-thread engine; natively, the 10 second clip took 5.1 seconds.
- The picture scored SSIM 0.959 against the source (1.0 would be identical).
- Next to it: WebM to AAC (-92.2%), WebM to AVI (+25.1%), WebM to FLAC (-24.0%).
Measured: WebM to MOV
The converter's own ffmpeg arguments, run on a 10 second 1920 × 1080 excerpt of Big Buck Bunny (an animated film, not camera footage) saved in WebM. The browser column is the same arguments on the single-thread WebAssembly core with a 3 second excerpt, in a headless run; your device will differ. Results describe this clip and these encoders.
| Check | Result |
|---|---|
| Mode | Re-encoded |
| Input | WebM, 2.11 MB |
| Output | MOV, 3.20 MB (+51.9%) |
| Output streams | Video: h264 1920x1080; Audio: aac 48000 Hz 2 ch |
| Time, native, 10 s clip | 5.1 s |
| Time, browser engine, 3 s clip | 31.7 s |
| Picture similarity (SSIM) | 0.959 |
A re-encode decodes and encodes every frame or sample, so the time grows with the length of the file.
WebM vs MOV
| WebM | MOV | |
|---|---|---|
| Full name | WebM (open web format) | QuickTime File Format (Apple) |
| What is inside | VP8, VP9 or AV1 video with Vorbis or Opus audio | H.264, HEVC or ProRes video with AAC or PCM audio |
| Compression | Lossy | Depends on the codec inside |
| Best for | Video on web pages; YouTube accepts it, most short-form apps do not | iPhone recordings and Final Cut Pro projects |
What you get
H.264 video and AAC audio in a QuickTime MOV. VP8/Opus re-encoded to H.264/AAC inside MOV.
Where you can upload MOV
| Platform | MOV | What the platform documents |
|---|---|---|
| TikTok | Accepted | Yes - TikTok documents MOV uploads through its Content Posting API. |
| Instagram Reels | Accepted | Yes - Instagram accepts MOV as well as MP4 for Reels. |
| Instagram Feed | Accepted | Yes - Instagram accepts MOV as well as MP4 for feed videos. |
| YouTube Shorts | Accepted | Yes - YouTube (and Shorts) accepts MOV uploads directly. |
| X (Twitter) | Partly | Yes in X Media Studio - MOV support in other X upload surfaces is not established here. |
| Facebook Reels | Unclear | Current MOV support for Facebook video uploads has not been reverified. |
| Partly | Partially - MOV works from the Pinterest app, but not on the web uploader. | |
| Accepted | Yes - LinkedIn documents MOV for organic video on desktop, iOS and Android. | |
| Snapchat | Unclear | MOV support for Spotlight is not established by the linked Snapchat help page. |
| Threads | Unclear | Current MOV upload support on Threads has not been reverified. |
Planning a bigger file
These are estimates scaled up from the 10 second clip. Real files differ with content, resolution and bitrate, so treat them as an order of magnitude, not a promise.
| Length of the video or recording | Input size (like ours) | MOV size | Time in your browser |
|---|---|---|---|
| 1 minute | 12.62 MB | 19.18 MB | 11 minutes |
| 10 minutes | 126.24 MB | 191.79 MB | 106 minutes |
| 1 hour | 757.44 MB | 1150.73 MB | 635 minutes |
A WebM file of this kind reaches the 100 MB limit of the converter after about 8.3 minutes; converting it would take roughly 88 minutes on the single-thread engine, and the MOV would be about 159.30 MB.
WebM and MOV next to their neighbors
The same clip through other conversions with the same source or the same target.
| Conversion | How | Size change | Time (native) |
|---|---|---|---|
| WebM to MOV | Re-encode | +51.9% | 5.1 s |
| WebM to AAC | Re-encode | -92.2% | 0.32 s |
| WebM to AVI | Re-encode | +25.1% | 1.5 s |
| WebM to FLAC | Re-encode | -24.0% | 0.13 s |
| WebM to M4A | Re-encode | -92.3% | 0.31 s |
| WebM to MKV | Re-encode | +51.6% | 5.0 s |
| WebM to MP3 | Re-encode | -92.4% | 0.25 s |
Choosing MOV
MOV: QuickTime File Format (Apple). iPhone recordings and Final Cut Pro projects. WebM: WebM (open web format). Video on web pages; YouTube accepts it, most short-form apps do not.
- Keep your original: a re-encode is a copy of a copy.
- If the destination states the format it accepts, use that and nothing else.
Questions people ask
Is this WebM to MOV 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 WebM to MOV reduce quality?
Some, because MOV is depends on the codec inside and the file is re-encoded. How much depends on the clip and on the quality setting, and at the converter's default setting the loss can be visible, so keep the original. For uploads, the platform re-encodes again anyway.
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.
How do I convert WebM to MOV?
Choose the file in the converter above and download the MOV. It runs in your browser with no upload.
Will converting WebM to MOV reduce quality?
A little. The picture scored SSIM 0.959 against the source in our test.
Why did the file size change by +51.9%?
The target codec and settings decide the size. This 10 second clip came out at 3.20 MB.
How long does it take?
A 3 second clip took 31.7 seconds in the browser engine in our test; time grows with the length of the file.
How long will a WebM file of 100 MB take?
At the speed we measured in the browser engine, about 88 minutes for a file like our clip. Your device and the content will change it.
Is my file uploaded?
No. The conversion runs in your browser.
Is there a size limit?
Files up to 100 MB. The first conversion downloads a converter engine of about 30 MB once per visit.
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 2026-10-09)
- MDN: Media container formats (read 2026-10-09)
- Blender Foundation: Big Buck Bunny (CC BY 3.0), the clip used for the measurements (read 2026-10-09)
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.