What is a WebM file?
WebM stands for WebM video. It was created by Google and first released in 2010. WebM is a royalty-free subset of Matroska made for the web. Browser screen recorders and many online meeting tools save to WebM, which iMovie and many editors cannot import.
| Type | video |
|---|---|
| Compression | Lossy |
| Usually contains | VP8, VP9 or AV1 video with Vorbis or Opus audio |
| In a browser | plays in Chrome, Firefox and Edge, and in Safari since version 14.1 |
| Common uses | web video, screen recorders and browser-based recordings |
| MIME type | video/webm |
Which format should you convert WebM to?
- WebM to MP4 to play on any phone, computer or TV, or to upload to YouTube and social media.
- WebM to MOV to edit in iMovie or Final Cut Pro on a Mac.
- WebM to MP3 to keep only the soundtrack, for music or a podcast.
- WebM to GIF to share a short silent clip that loops anywhere.
WebM is already lossy, so converting it to a lossless format makes the file bigger without improving it; pick a lossless target only if a program requires one.
How to open a WebM file
Whether a WebM file opens with a double click depends on the device. Here is what works on each, without buying software:
| Windows | Films and TV and Media Player open the common formats; VLC opens almost any video file, WebM included. |
|---|---|
| Mac | QuickTime Player opens formats Apple supports; VLC or IINA open the rest. |
| iPhone and iPad | The Files app plays formats Apple supports. For others, a player such as VLC for iOS, or converting the file here, is the easiest route. |
| Android | Most gallery and music apps play the common formats; VLC for Android plays almost everything. |
| Web browser | WebM plays in Chrome, Firefox and Edge, and in Safari since version 14.1. |
Want the technical details? See what a .webm file is, with its MIME type, file signature and a viewer.
WebM compared with other video formats
How WebM stacks up against the formats people most often convert it to or from:
| Format | Compression | Usually contains | Released | Best for |
|---|---|---|---|---|
| WebM | Lossy | VP8, VP9 or AV1 video with Vorbis or Opus audio | 2010 | web video, screen recorders and browser-based recordings |
| MP4 | Lossy | H.264 or H.265 video with AAC audio | 2001 | phone videos, YouTube uploads, social media and streaming |
| MOV | Lossy | H.264, HEVC or ProRes video with AAC audio | 1991 | iPhone recordings, Final Cut Pro and screen recordings on Mac |
| MKV | Lossy | almost any codec, often H.264 or H.265 with several audio and subtitle tracks | 2002 | films and TV rips, OBS recordings and anime releases |
| AVI | Lossy | MPEG-4 Part 2 (Xvid, DivX), MJPEG or uncompressed video with MP3 or PCM audio | 1992 | older camcorders, digital cameras and legacy video libraries |
How to use the WebM converter
- Choose the format you want in the Convert to menu.
- Drop your WebM files on the box, or press Choose WebM files. Several files can go in at once.
- Adjust the settings if you need to; the defaults suit most people.
- Press Convert and save each file with its Download button. Nothing is uploaded at any point.
Tips for converting WebM files without losing quality
WebM is lossy, so some detail was already discarded when the file was made. Converting it cannot bring that back. Converting to a lossless format preserves what is left exactly but makes the file larger; converting to another lossy format adds a small extra loss, which is invisible at sensible settings.
- Keep the original recording. Every re-encode costs a little detail, so convert from the best copy you have, not from a file that was already converted.
- Know whether you need a new container or a new codec. MOV, MKV and MP4 can all hold H.264 video, and switching between them is fast and lossless; changing the codec means re-encoding, which is slower.
- For sharing, MP4 with H.264 at 1080p or 720p is the safe choice: every phone, browser and social network plays it.
- Phones record at very high bitrates. If a file is too big to send, lowering the resolution to 720p usually shrinks it far more than any quality setting.
Convert WebM files from the command line
Everything this page does can also be done in a terminal. The most common WebM conversion, to MP4, looks like this with ffmpeg:
ffmpeg -i input.webm -c:v libx264 -crf 23 -preset veryfast -c:a aac -b:a 128k -movflags +faststart output.mp4Change the output extension to pick another format. The converter above runs the same ffmpeg engine inside your browser, so you get the result without installing anything.
WebM converter FAQ
What is a WebM file?
WebM stands for WebM video, a video format created by Google in 2010. WebM is a royalty-free subset of Matroska made for the web. Browser screen recorders and many online meeting tools save to WebM, which iMovie and many editors cannot import.
How do I open a WebM file?
WebM plays in Chrome, Firefox and Edge, and in Safari since version 14.1. If the program you need will not open it, convert it to a more widely supported format above.
What is the most common WebM conversion?
WebM to MP4 is the conversion people search for most. The video is re-encoded to H.264 video with AAC audio.
Does converting WebM files here upload them?
No. Every conversion on this page runs inside your browser, so your WebM files never leave your device.
Is the WebM converter free?
Yes. There is no sign-up and no watermark, and no limit on how many WebM files you convert. The site is supported by advertising.
Can I convert WebM files on iPhone or Android?
Yes. Open this page in Safari on iPhone and iPad, or in Chrome on Android, choose your WebM files and download the results to your Downloads folder.
Can I convert several WebM files at once?
Yes. Drop as many as you like; they are converted one after another, each with its own download button.