What is a WebM file?
WebM is a free video format built for web pages, so browsers play it with no plugin and no licence behind it. Files come out smaller than the same clip as MP4, but fewer phones and editors will open one. You can convert WebM files here, both into the format and out of it.
Specification
| Full name | WebM |
|---|---|
| Extensions | .webm |
| Media type | video/webm |
| Compression | Lossy |
| Transparency | Supported |
| Animation | — |
| Multiple pages | — |
| Colour depth | — |
| Size limits | — |
| Introduced | 2010 |
| Developed by | |
| Standard | Open |
| Browser support | All current browsers |
What WebM is used for
- HTML5 video where licence-free delivery is required
- Replacing animated GIFs with something an order of magnitude smaller
- Video that needs a transparent background on a web page
- WebRTC recordings and browser-captured media
Strengths and limitations
What WebM does well
- Completely royalty free
- Noticeably smaller than MP4 at the same visual quality
- Can have a see-through background, which MP4 in practice cannot
Where WebM falls short
- Safari came to it late, and playback is uneven on older devices
- Many TVs, editors and older devices will not open it
- Slower to produce than an MP4 of the same clip
Convert WebM to
Every target this format can be written out as, each on its own page.
Convert to WebM
Everything that can be turned into a WebM file.
Tools that accept WebM
Questions about WebM
What is a .webm file?
WebM is a free video format built for web pages, so browsers play it with no plugin and no licence behind it. The extension .webm identifies it, and its media type is video/webm.
How do I open a WebM file?
Any current browser will open it directly, so dragging the file into a tab is usually enough. Most operating systems also preview it without extra software.
Is WebM lossy or lossless?
Lossy. That means detail is discarded during encoding and each re-save compounds the loss, so keep an untouched master where quality matters.
What is WebM good for?
Completely royalty free. Noticeably smaller than MP4 at the same visual quality. Can have a see-through background, which MP4 in practice cannot. In practice that makes it a good fit for HTML5 video where licence-free delivery is required, and Replacing animated GIFs with something an order of magnitude smaller.
What are the drawbacks of WebM?
Safari came to it late, and playback is uneven on older devices. Many TVs, editors and older devices will not open it. Slower to produce than an MP4 of the same clip.