WebM to MP4 Converter: Make Web Videos Play Everywhere
Convert WebM videos (VP8, VP9, AV1) to MP4 with H.264 and AAC in your browser, so they play on iPhone, in PowerPoint and in every editor. No upload.
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Your files never leave your device
About this tool
This WebM to MP4 converter turns WebM videos into MP4 files that work on any device. WebM is Google's open web video format, usually holding VP8 or VP9 video with Opus audio. Browsers play it well, but iPhones, PowerPoint, Premiere, WhatsApp status and many TVs still expect MP4 with H.264. The conversion runs in your browser, so the video stays on your device.
How to convert WebM to MP4
- Drop the WebM file on the page or click to choose it.
- Check the codecs shown in the panel. VP8, VP9 and AV1 video will be re-encoded to H.264.
- Pick High quality for the closest match, or Balanced for a smaller file.
- Click Convert to MP4, watch the progress, then preview and download the MP4.
Where WebM files come from
| Source | Usual codecs | Result |
|---|---|---|
| Browser screen recorders, Loom, web cams in Chrome | VP8 or VP9 + Opus | Re-encoded to H.264 + AAC |
| Chrome recordings set to H.264 | H.264 + Opus | Video copied, audio to AAC |
| Downloaded web videos | VP9 or AV1 + Opus | Re-encoded to H.264 + AAC |
| Old WebM clips | VP8 + Vorbis | Re-encoded to H.264 + AAC |
Tips for WebM files
- Screen recordings made in the browser often have no duration in the file, so players cannot seek. The MP4 you get here has a proper duration and seeks normally.
- Text and code on screen stay crisp with High quality. Balanced is fine for camera footage.
- Re-encoding takes time: a few minutes of 1080p usually converts in about a minute on a recent laptop with hardware H.264.
- Too big for email after converting? Shrink it with the video compressor.
Private by design
The WebM is decoded and encoded on your device with the browser's WebCodecs engine and your hardware encoder. Nothing is uploaded, so screen recordings with private data stay private. Want a looping animation instead? Use the video to GIF converter.
Features
- Converts WebM with VP8, VP9 or AV1 video
- Output is MP4 with H.264 video and AAC audio
- Opus or Vorbis audio converted to AAC stereo
- H.264 WebM recordings are copied without re-encoding
- High quality or Balanced preset with a live progress bar
- Runs in your browser: the video is never uploaded
Frequently asked questions
How do I convert WebM to MP4?
Drop the WebM file on this page, choose High quality or Balanced and click Convert to MP4. When it finishes, preview the MP4 and download it.
Why does WebM to MP4 take longer than other conversions?
WebM usually holds VP8 or VP9 video, which MP4 players rarely support, so the video must be re-encoded to H.264. Your device's hardware encoder keeps this fast.
Does converting WebM to MP4 lose quality?
Re-encoding always changes the video slightly, but the High quality preset keeps it visually very close to the original. WebM files recorded in H.264 are copied with no loss.
Why won't my WebM play on iPhone or in PowerPoint?
Many apps, older iPhones and Office do not support VP9 or VP8 video inside WebM. MP4 with H.264 and AAC is supported by all of them.
Is my WebM file uploaded?
No. The conversion runs entirely in your browser. The file never leaves your computer or phone.
Can I convert a screen recording to MP4?
Yes. Screen recordings saved as WebM by Chrome, Loom or other browser recorders convert to MP4, and the result gets a correct duration so it seeks properly.