About the WebM to MP4
WebM files come from screen recorders, browser downloads and web apps, but many phones, TVs, editing programs and upload forms expect MP4. This converter turns WebM into MP4 in your browser. The VP8, VP9 or AV1 video is re-encoded to H.264 where possible, the most compatible codec, and the sound to AAC, so the MP4 plays almost anywhere. You can preview it before downloading, and nothing is ever uploaded.
Updated October 2026
How to use the WebM to MP4
- 1Select a WebM video.
- 2Press Convert to MP4.
- 3Wait for the progress bar.
- 4Play the preview to check it.
- 5Download the MP4.
Where WebM files come from
Browser-based screen recorders, Loom-style tools, some video downloads, Telegram and Discord clips, and many web apps save WebM, because browsers can record it natively.
Sound in WebM
WebM sound is usually Opus. MP4 can hold Opus, but older players can't play it, so the converter uses AAC when your browser can encode it. If the sound can't be converted in your browser, the tool tells you.
How it works without uploading
Your browser has a built-in video engine (WebCodecs) that phones and computers use to play and record video. This tool uses it through Mediabunny, an open-source media library, to read your file, change it and write a new one, all inside the page. Speed depends on your device: a recent phone or laptop handles a few minutes of HD video comfortably, while long 4K files take longer.
Editing the result
MP4 files open in iMovie, Premiere, DaVinci Resolve, CapCut and Windows Clipchamp, so converting is the usual first step before editing a WebM recording.
Fixing recordings that won't seek
WebM files from some browser recorders don't store their duration, so players can't show a progress bar or let you jump around. Converting to MP4 writes a complete file with a proper index, which fixes seeking and shows the correct length everywhere.
Codec used for the MP4
The converter asks your browser for an H.264 encoder first, because H.264 plays on everything from old phones to smart TVs. If H.264 isn't available, it uses the next codec MP4 can hold, such as HEVC or AV1, and the preview shows whether it plays on your device.
Phone and computer
Convert on any modern browser; Chrome and Edge are fastest for long recordings. To go back to WebM use MP4 to WebM, and the Video Converter lists other types.
Features
- WebM to widely playable MP4
- Handles VP8, VP9 and AV1
- Ideal for screen recordings
- Preview before download
- No upload
- No watermark
Frequently asked questions
Why won't my WebM file play?
Some players, older Windows versions, iPhones apps and editing programs don't support WebM. MP4 with H.264 plays on practically everything.
Will the MP4 look the same?
Yes. It is re-encoded at high quality, so differences are very hard to see.
Can I convert screen recordings from Chrome?
Yes. Screen recorders built into browsers usually save WebM, including our Screen Recorder, and this tool converts them for sharing.
Why is the MP4 bigger than the WebM?
VP9 and AV1 are more efficient than H.264, so the MP4 can be larger at the same quality. Use the Video Compressor to shrink it.
Which browsers work best?
Chrome and Edge on computers and Android support the most video formats. Safari 16.4+ and recent Firefox work too, but some codecs, such as HEVC in Firefox, may not be supported there.
Is my video uploaded?
No. It is processed on your own device with your browser's built-in video engine, so private videos never leave your phone or computer.
Does it keep the original resolution?
Yes. The MP4 has the same width, height and frame rate as the WebM.
Can I convert on an iPhone?
Yes, in Safari on iOS 16.4 or later. If Safari can't decode a particular WebM codec, try the conversion on a computer with Chrome or Edge.