All formats
MP4 vs WebM
MP4 with H.264 plays on everything: phones, TVs, editors, browsers. WebM with VP9 is typically 30 percent smaller at the same quality but plays essentially only in browsers. Serve WebM to browsers with an MP4 fallback, and hand out MP4 to people.
Side by side
| Spec | MP4 | WebM |
|---|---|---|
| Type | Video | Video |
| Extensions | .mp4, .m4v | .webm |
| Introduced | 2001 | 2010 |
| Compression | Lossy | Lossy |
| MIME type | video/mp4 | video/webm |
| Use it when | Any video that must simply play, anywhere, without the recipient thinking about it. | Web delivery you control, especially if you need transparency or want to avoid codec licensing. |
| Avoid it when | You need a fully royalty-free pipeline. Use WebM. | The file goes to a client, a video editor, or an unknown device. Use MP4. |
Where the usual answer breaks
Video needing a transparent background. WebM supports an alpha channel in VP9; standard MP4 does not.
MP4
- Plays on effectively every device, browser and editor
- Efficient compression with H.264 or H.265
- Supports subtitles, chapters and multiple audio tracks
- H.264 and H.265 carry patent licensing obligations in some contexts
- Larger than an equivalent AV1 or VP9 encode
WebM
- Royalty-free, with no codec licensing to consider
- Smaller than H.264 MP4 at equivalent quality
- Supports video with an alpha (transparency) channel
- Weaker support in desktop editors and on older Apple hardware
- VP9 and AV1 encoding is slower than H.264
Convert between MP4 and WebM
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Last updated 2026-08-03