WebM to MP4 converter
Turn WebM clips into MP4 files that open anywhere.
Runs in your browser. Your files never leave your device.
- Batch convert
- H.264 and AAC output
- Nothing uploaded
How to convert WebM to MP4
- Drop your WebM files here.
- Each one converts to MP4.
- Download the MP4 files.
Why WebM needs a full re-encode
WebM video is normally VP9 or VP8, and its audio is Opus. MP4 has no way to store either directly, so both tracks are decoded and re-encoded, video to H.264 and audio to AAC, rather than simply moved into a new container.
WebM vs MP4
| WebM | MP4 | |
|---|---|---|
| Video codec | VP9 or VP8 | H.264 |
| Audio codec | Opus | AAC |
| Safari support | Inconsistent across versions | Full support |
| Common source | Browser recorders, some web video | Cameras, phones, most editors |
WebM has been around since 2010, built specifically so websites could offer video without licensing fees. MP4 is older and backed by wider hardware support, which is why it remains the safer choice once a video leaves the browser and needs to open reliably on someone else's device.
WebM to MP4 FAQ
Why convert WebM to MP4?
WebM is common for screen recordings and web video, but many phones, video editors and older TVs only accept MP4.
Does this re-encode the video?
Yes. WebM usually uses VP9 or VP8 video, which MP4 cannot store directly, so the video is re-encoded to H.264 at a fixed high quality. This takes longer than a straight copy but keeps the result looking close to the original.
Is there a file size limit?
No fixed limit. Large files just take longer and depend on your device.
Where do WebM files usually come from?
Browser-based screen recorders, video calls saved locally, and some websites that serve WebM instead of MP4 for smaller downloads.
Will the audio also change?
Yes. WebM's Opus audio is re-encoded to AAC, which is what MP4 expects.
Can I convert a WebM screen recording made on this site?
Yes. A recording from the screen recorder tool here is a normal WebM file and converts the same way as any other.
Why does Chrome save video as WebM instead of MP4?
WebM was built by Google as a royalty-free format for the web, and Chrome's built-in tools, like tab and screen recording, default to it rather than the more restrictively licensed MP4 codecs.
Are my clips uploaded?
No. The conversion happens on your device.
Can I convert a WebM voice recording from the voice recorder tool here?
No, not on this page. A voice recording is audio-only WebM with no video track, and this tool expects a video, so it will show a no video track error. Use the audio converter instead for an audio-only WebM file.