MP4 vs WebM
| Property | MP4 | WebM |
|---|---|---|
| Full name | MPEG-4 Part 14 | WebM (based on Matroska) |
| File extensions | .mp4, .m4v | .webm |
| Created by | MPEG (ISO/IEC 14496-14) | |
| Introduced | 2003 | 2010 |
| Compression | Depends on the codec inside; usually lossy | Lossy (VP8, VP9 or AV1) |
| Codecs inside | Usually H.264 or H.265 video with AAC audio | VP8, VP9 or AV1 video; Vorbis or Opus audio |
| Opens on | Every phone, computer, TV, browser, editor and social network | Every current browser and Android; many editors, older iPhones and TVs do not play it |
| Best for | Sharing, uploading and playing video anywhere | Video on websites and browser screen recordings |
Why convert MP4 to WebM?
WebM is the open video format of the web. Developers use it for autoplaying hero and background videos, product loops and animations, often alongside an MP4 fallback in a <video> element. Wikipedia and Wikimedia Commons accept WebM but not MP4, and some open-source projects and game engines prefer it too.
VP9 usually compresses better than H.264 at the same quality, so a WebM can be smaller than the MP4 it came from. The trade-off is encoding time: VP9 is slower to encode, and fewer devices have a hardware VP9 encoder, so expect conversion to take longer than real time for 1080p on many computers. Short clips are the sweet spot.
For sharing with people rather than embedding on a site, MP4 remains the better choice. To shrink an MP4 while keeping it MP4, use the Video Compressor.