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WebM to MP4 converter

Turn a WebM screen recording or web download into an MP4 that iPhones, PowerPoint and editing apps accept.

Runs in your browser. Your file is never uploaded.

How to convert WebM to MP4

  1. 1Drop one or more WebM files into the box above.
  2. 2MP4 is already selected. Pick a lower resolution if you want a smaller file.
  3. 3Select Convert and download the MP4.

What you get

  • WebM uses VP8 or VP9 video, so it's always re-encoded to H.264 with AAC sound for MP4. That takes longer than copying, roughly the length of the video or less on a recent computer.
  • Screen recordings from Chrome, OBS and similar apps come out at the same size and frame rate.
  • The main video and the first sound track are kept. Subtitle tracks, extra audio languages and chapters are left out.
  • Up to 3 files at a time free, or 30 with Pro.

Limits

  • Free, with or without an account: files up to 500 MB, 3 at a time.
  • With Pro: files up to 2 GB, 30 at a time.
  • Big files are read from your disk as they're processed, so they don't need to fit in memory, but a phone takes longer than a computer.

What happens to your file

Your file never leaves your device. The conversion runs in your browser using code from our site, and we don't receive the file, its name or anything inside it. How we handle files.

WebM to MP4: common questions

Is this WebM to MP4 converter free?
Yes. Files up to 500 MB convert free, without an account and without a watermark. Pro raises the limit to 2 GB a file and converts up to 30 files at a time.
Why won't my WebM play on my iPhone or in PowerPoint?
Older iPhones and some versions of PowerPoint and Windows Media Player don't support WebM. MP4 with H.264 plays on all of them.
Does it keep the sound?
Yes. The WebM's Opus or Vorbis sound is converted to AAC, which MP4 players expect.
Is my recording uploaded?
No. The conversion runs in your browser, so the recording stays on your device and never reaches our server. Once the page has loaded it keeps working if your connection drops.
Why does the first conversion take a few seconds to start?
The converter is a copy of FFmpeg that runs in your browser. It's about 31 MB, so it downloads the first time you use it and your browser keeps it for next time.

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