Compress a WebM video (and convert it to MP4)
WebM (VP8/VP9 video) is what many browser-based recorders and web tools produce. It's efficient, but some apps and older Apple devices don't play it well. Compressing here converts WebM to H.264/AAC MP4 at the size you choose, giving you a file that plays essentially everywhere.
Last updated September 2026
Compress a WebM →How to do it
- Open the compressor.
- Load your .webm file.
- Pick a preset or custom target size.
- Lower resolution for long recordings.
- Compress and download the MP4.
Tips
- WebM is already efficient, so converting at a similar bitrate may not shrink it much — pick a smaller target.
- Some browser-recorded WebMs lack duration metadata; if the size estimate looks off, trimming can help.
- Opus audio is re-encoded to AAC for MP4 compatibility.
FAQ
Does it convert WebM to MP4?
Yes. The output is always H.264/AAC MP4.
Why doesn't my WebM play on iPhone?
Support for WebM varies across Apple apps and older iOS versions. MP4 with H.264 is universally supported.
Is my file uploaded?
No — conversion and compression happen in your browser.