WebM → MP4

WebM to MP4 Converter — Free, No File Size Limit

No file size limit up to 500 MB — typical 1080p clip converts in 10–15 seconds
QUICK ANSWER

How to convert a WebM to MP4 in three clicks: drop your file, hit Convert, download. No upload, no signup, no watermark, and no file size cap up to 500 MB. Works on screen recordings, OBS captures, Loom downloads, and any browser MediaRecorder output. H.264 + AAC output plays on every device — iPhone, Windows Media Player, and every social platform that accepts MP4.

  • No file size limit (up to 500 MB)
  • Free forever
  • No signup
  • No watermark
  • Universal MP4 output
  • H.264 + AAC
  • Runs in your browser

Files never leave your browser. The conversion runs locally on your device.

Trusted by creators at startups, agencies, and Fortune 500 teams.
Free forever — no signup, no watermark, no length cap.

How it works

  1. 1

    Drop your WebM file

    Drag any .webm file in or click to choose. Files up to 500 MB are supported — no account required.

  2. 2

    Click Convert to MP4

    We transcode VP8/VP9 video to H.264 at CRF 22 and Opus audio to AAC at 160 kbps. Output is muxed into MP4 with +faststart for instant streaming playback. Most 1080p clips finish in 10–15 seconds.

  3. 3

    Download your MP4

    Hit Download. The output plays on every device, every browser, and every social platform that takes MP4 uploads.

When you need to convert a WebM to MP4

Every browser-based screen recorder hands you a .webm — Chrome's built-in recorder, OBS's WebRTC mode, Loom downloads, our own Clipy web recorder. Most of the time the next thing you want to do is upload to iMessage, drop in a Slack DM, or send to a Windows colleague — and that is when the universal-compatibility gap bites. Converting WebM to MP4 once solves it permanently.

No file size limit — up to 500 MB

Most browser-based converters impose a 50–200 MB cap because they process files on their own servers and pay per gigabyte. This tool runs entirely in your browser via FFmpeg compiled to WebAssembly, so there is no server cost and no artificial cap. The only real ceiling is the WebAssembly memory limit in your browser tab, which is around 500 MB for most modern browsers. For files beyond that, the Clipy desktop app ships native FFmpeg with no memory ceiling at all.

Adjacent tools

Going the other direction? Convert MP4 to WebM — re-encodes to VP8 + Vorbis for HTML5 video, Google Slides embeds, and open-source players. Already have a working MP4 you want to compress further? Video compressor.

Why convert WebM to MP4?

WebM is what Chrome's MediaRecorder API outputs by default, so it's what most browser-recorded video starts as — Loom downloads, Clipy's web recorder, OBS WebRTC streams. The problem: WebM doesn't play in iMessage, in Safari without dependencies, in Windows Media Player, or on most social platforms that take video uploads. MP4 is the universal answer.

What is WebM?

WebM is an open-spec container built around VP8/VP9 video and Vorbis/Opus audio, championed by Google and Mozilla as a royalty-free alternative to MP4. Excellent for in-browser playback (every modern browser supports it natively) but poor compatibility outside the browser.

What is MP4?

MP4 (ISO/IEC 14496-14) is the dominant container on the web. With H.264 video + AAC audio inside, it plays natively in every browser, every mobile OS, every smart TV, and every video-accepting social platform.

Common questions

Is there a file size limit for converting WebM to MP4?

Up to 500 MB. The WebAssembly build of FFmpeg runs in your browser tab, and that is the practical memory ceiling. For files larger than 500 MB, use the desktop Clipy app — it runs native FFmpeg with no memory cap.

How do I convert a WebM file to MP4?

Drop the .webm file onto this page, click Convert to MP4, then click Download. The whole process takes 10–15 seconds for a typical 1080p clip. No account, no install, no upload required.

Why is converting WebM to MP4 not instant?

VP8/VP9 (inside WebM) and H.264 (inside MP4) are different codecs, so every frame must be decoded and re-encoded. This is a true transcode, not a remux. A 1080p clip takes 10–15 seconds for every minute of source on a modern laptop.

Will I lose quality?

There is a small one-generation quality loss on the re-encode — typically imperceptible at CRF 22 unless you do a side-by-side comparison. For pure archival quality, keep the original WebM.

Why is the audio quieter than I expected?

We convert audio to AAC at 160 kbps. If you need to boost levels, use the desktop app or run the output through a separate audio normalizer.

Is the file uploaded anywhere?

No. The conversion runs in your browser via FFmpeg compiled to WebAssembly. Verify in your network tab — there is no upload request.

Does this work on mobile?

Yes on modern iOS Safari and Chrome / Edge on Android, though large files may hit WebAssembly memory limits.

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