Convert WebM to MP4
Web videos and browser recordings that play on any device.
Convert WebM videos to MP4 to play them on an iPhone, send them through WhatsApp, insert them in PowerPoint or open them in a video editor. WebM is the format of many screen recordings made in the browser and of videos downloaded from the web; MP4 in H.264 works everywhere else.
How to convert WebM to MP4
- Select your WebM video (up to 100 MB).
- Click “Convert to MP4”.
- Wait while we re-encode the video: it usually takes a few seconds.
- Download the MP4.
Why convert WebM to MP4
WebM was created by Google for the web: browsers play it without problems and it compresses very well with the VP8, VP9 or AV1 codecs. Outside the browser, it is another story:
- The iPhone’s Photos app, WhatsApp and many messaging apps don’t accept it as a video.
- PowerPoint, Keynote, iMovie and many editors don’t open it.
- TVs and consoles often don’t play it.
MP4 with H.264 image and AAC sound works in all of them.
What you get
- H.264 video with the same resolution and frame rate as the original (up to 4096 pixels on the longest side, the maximum that phones and browsers play in H.264).
- AAC sound, converted from the Opus or Vorbis that WebM files carry.
- No metadata, and the index at the start of the file so it starts playing before it has fully downloaded.
Limitations
- Transparency is lost: a WebM with a transparent background (some animations and stickers) becomes an opaque video, because H.264 has no transparency.
- WebM is always re-encoded, so very long videos have to be trimmed first; the message will tell you the maximum.
- One video at a time, up to 100 MB. For a short clip as an animation, use WebM to GIF.
Frequently asked questions
Why won’t my iPhone play a WebM video?
Because the Photos app and most iPhone apps only accept MP4 and MOV. Safari can play WebM in a web page, but to save the video, send it or edit it on the iPhone you need it in MP4.
Why is the MP4 larger than the WebM?
Because VP9 and AV1, the codecs of many WebM files, compress better than H.264. The MP4 can take up somewhat more space, but in exchange it plays on practically any device.
Can I convert a screen recording made in the browser?
Yes. Many browser extensions and online recorders save in WebM: converting the recording to MP4 lets you edit it, put it in a presentation or send it through any messaging app.
What happens to a WebM with a transparent background?
The transparency is lost, because the H.264 video in an MP4 doesn’t support it. If you need transparency, keep the WebM for browsers or use an animated format such as GIF.