How to convert WebM to MP4
- Drop your WebM file in.
- Check the details: WebM files are re-encoded to H.264 so the MP4 plays everywhere.
- Press “Convert to MP4” and save the new file.
Why WebM files cause trouble
WebM is the format browsers and many screen recorders use. It usually holds VP8 or VP9 video with Opus sound. Browsers play it fine, but iPhones, many Windows apps, video editors, TVs and social upload forms often don’t. MP4 with H.264 video and AAC sound is the format that works almost everywhere.
What happens to the quality
Because the video codec changes, every frame is re-encoded at high quality. For screen recordings, which have large flat areas, the result is usually indistinguishable from the original and often a similar size.
Common sources of WebM files
- Browser-based screen recorders and meeting recordings
- Videos saved from web pages
- Clips from some game capture and streaming tools
Questions
Will the MP4 work on my iPhone?
Yes. The output uses H.264 video and AAC sound, which every iPhone plays.
Why does it take longer than MOV to MP4?
MOV files can often be repackaged without re-encoding. WebM uses different codecs, so every frame has to be re-encoded.
Is there a watermark?
No. The video you save is exactly what the encoder produced: no watermark, no logo, no sign-up.
Is my video uploaded anywhere?
No. The tool runs inside your browser and uses your device’s own video encoder. Your file is read from your device, processed there and saved back. You can confirm this in your browser’s network panel: nothing is sent while a video is processed.
Which browsers does it work in?
It works best in Chrome and Edge on a computer. It needs a browser feature called WebCodecs. If your browser doesn’t have it, the page tells you before you start.