Convert WebM to MP4
Turn WebM recordings into MP4 that plays on every phone, computer and editor.
Runs in your browser. Your video is never uploaded.
Drop WebM files to convert to MP4
Screen recordings, meeting recordings and web downloads. Choose several to convert them all.
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How to convert WebM to MP4
Drop your WebM files above and press Convert to MP4. Each file becomes an MP4 with H.264 video and AAC audio. With one file you can watch the result before saving it; with several you get a list to save from, or a single ZIP. Nothing is uploaded, so even a long screen recording converts without waiting for a transfer.
Why WebM files need converting
WebM is the open video format of the web. Chrome, Firefox and Edge record and play it natively, which is why screen recorders, browser extensions, web cameras and many meeting tools save WebM. Outside the browser it is far less welcome: iPhones and iPads do not open it in Photos, many smart TVs and car screens cannot play it, popular editors ask for MP4 or MOV, and plenty of upload forms reject it outright.
MP4 with H.264 video and AAC audio is the format everything accepts. Converting gives you a file you can send to anyone, drop into any editor, or upload anywhere.
What happens to the video
A WebM file almost always holds VP8 or VP9 video. Those codecs can technically be placed inside an MP4, but phones, TVs and editors that expect MP4 generally cannot play them, so the converter decodes each frame and re-encodes it as H.264 using your device's hardware encoder, at a quality setting high enough that the difference is not visible at normal sizes. Some WebM recordings made in Chrome already contain H.264 video; those are copied straight into the MP4 with no re-encoding at all, and the result card tells you when that happened.
The audio in WebM is Opus or Vorbis. It is converted to AAC, which every MP4 player supports, and stays in sync with the picture.
Converting long recordings
Re-encoding takes time in proportion to the length of the video, but hardware encoding typically runs several times faster than real time — an hour-long meeting recording usually converts in minutes, not an hour. Keep the tab in front while it works: browsers pause video encoding in background tabs, and the page tells you if that happens.
Related tools
Converting the other way, for faster web pages? Use Convert to WebM. For iPhone and QuickTime files, MOV to MP4 is usually instant. To trim the start and end of a recording before sharing it, useCut & Merge, and to fit it under an upload limit use theVideo Compressor.
Frequently asked questions
How do I convert WebM to MP4?
Drop one or more WebM files above and press Convert to MP4. Each is converted to an MP4 with H.264 video and AAC audio, the combination that plays on iPhones, Windows, Macs, Android, TVs and in every video editor. Save each file or download them all as a ZIP.
Why won't my WebM video play on my iPhone or in my editor?
WebM is a web format, normally holding VP8 or VP9 video with Opus audio. Browsers play it, but many phones, TVs, editing apps and upload forms do not accept it. Converting to MP4 with H.264 video makes it playable everywhere.
Does converting WebM to MP4 lose quality?
Most WebM files use VP8 or VP9, which cannot go in a widely playable MP4, so the video is re-encoded to H.264 at a high quality setting — you should not see a difference at normal sizes. If the WebM already holds H.264, as recordings from Chrome sometimes do, the video is copied across untouched instead, and the result card says so.
Can I convert screen recordings and meeting recordings?
Yes. Screen recorders, browser extensions and many meeting tools save WebM files, and those convert like any other. Long recordings take longer because every frame is re-encoded, but your device's hardware encoder usually runs several times faster than real time.
What happens to the sound?
Opus or Vorbis audio, used in WebM, is converted to AAC, which MP4 players universally support. The sound stays in sync with the picture.
Are my files uploaded?
No. Everything happens in your browser. Your recordings never leave your device, which matters for private calls and screen captures.