WEBM → MP4
WEBM to MP4 converter
Drop a WEBM and get an MP4 that plays in any editor, phone or TV. The re-encode runs in this tab, so nothing is uploaded and nothing waits in a queue.
WEBM's VP9 video becomes H.264, which every device decodes. A long recording takes a while — the progress bar follows the encode, and you can leave the tab open.
At a glance
- Price
- Free
- Account
- None needed
- Upload
- None — the video is decoded and encoded in your browser tab, nothing is sent to a server
- Input
- WEBM
- Output
- MP4 (H.264 + AAC)
- File size
- 1 GB per file
- Works on
- Recent Chrome, Edge, Firefox or Safari (Firefox 130+, Safari 16.4+)
How to convert WEBM to MP4
Add the WEBM
Drop the file on the box above. One file at a time keeps the encode's memory inside what a browser tab can hold.
Convert
Press Convert to MP4 — optionally pick 1080p or 720p to shrink the result along the way. VP9 to H.264 is a real re-encode, so the bar moves with the work.
Download the MP4
When the bar fills, the file is ready with an .mp4 name. It plays in QuickTime, Windows Media Player, phones and every editor.
Why WEBM becomes MP4
WEBM is the web's own container: browsers record and stream with it, and it stays small thanks to the VP9 codec. MP4 with H.264 is the opposite — a little larger, but understood by literally every phone, TV, editor and social platform made in the last fifteen years.
The two do not share codecs, so nothing can simply be copied: the VP9 frames are decoded by your browser's own decoder and encoded again as H.264 by its hardware encoder. That is why the conversion takes about as long as watching the video — and why nothing ever leaves your device.
WEBM to MP4 questions
Is my file uploaded anywhere?
No. The video is decoded and encoded inside this browser tab using your device's own codecs. There is no server, no queue and no copy of your file anywhere but your disk.
Why does the conversion take as long as the video plays?
Because every frame is decoded and encoded again — VP9 and H.264 are different formats that cannot be copied between. Hardware encoders usually run several times faster than real time, and the progress bar shows the truth.
Does the MP4 lose quality?
A little; any re-encode does. At the original resolution with the default settings the loss is minimal, and you can keep the source WEBM if you want a reference copy.
Can I make the MP4 smaller?
Yes — pick 720p or 480p under Resolution to shrink the frame size while converting. For size control without changing resolution, convert first and then run the video compressor.
Will the audio survive?
Yes: Opus audio becomes AAC, which is what MP4 players expect. If the WEBM has no audio track, the MP4 simply has none either.