Convert an MP4 video to WebM to publish it on a website with open, royalty-free formats, upload it to Wikimedia Commons or use it in a tool that asks for WebM. We create it with VP9 video and Opus sound, which Chrome, Firefox and Edge play without plug-ins. One video at a time, up to 100 MB, with no sign-up.
How to convert MP4 to WebM
- Select your MP4 video (up to 100 MB).
- Click “Convert to WebM”.
- Wait while we re-encode the video: usually a few seconds.
- Download the WebM.
When WebM makes sense
WebM is the video format Google created for the web, free of patents and licence fees. It is the right choice when:
- You publish videos on your own website and prefer open formats, for example as a source of an HTML video element next to the MP4.
- You upload a video to Wikipedia: Wikimedia Commons asks for free formats such as WebM.
- A program or platform asks for WebM, as some web editors, animation tools and open-source projects do.
To send a video to someone, post it on social networks or play it on an iPhone or a TV, keep the MP4: it plays on more devices.
What the WebM contains
- VP9 video, re-encoded from the MP4, at a quality that keeps detail and movement.
- Opus sound at 128 kbit/s.
- Up to Full HD (1920 × 1080, or 1080 × 1920 in portrait): larger videos are scaled down to fit, and smaller ones keep their size.
- Videos recorded in HDR are converted to standard colour, so they don’t look washed out.
- Only the first video track and the first audio track, without metadata.
Limitations
- The WebM is not always lighter than the MP4: we use the fast VP9 mode so that the conversion doesn’t keep you waiting.
- Safari plays WebM on recent Macs, but on iPhone, iPad and many TVs and editing programs MP4 is still the safer option.
- The video is always re-encoded, so very long videos have to be trimmed first; the message tells you the limit. One video at a time, up to 100 MB.
- To go back to MP4, use WebM to MP4.
Frequently asked questions
Which browsers play WebM?
Chrome, Firefox, Edge and Opera on computers and Android phones, and Safari on recent Macs. On iPhone and iPad, and on many TVs, MP4 is still more reliable.
Is WebM smaller than MP4?
It depends on the video. VP9 can compress more than H.264, but to convert in seconds we use its fast mode, so the WebM can end up a little larger or a little smaller than the original MP4.
Can I upload the WebM to Wikimedia Commons?
Yes. Commons accepts videos in free formats, and a WebM with VP9 and Opus is one of them. Remember that Commons also asks for a free licence for the content of the video.
Does the video lose quality when converted to WebM?
A little, because it is always re-encoded, but at the quality we use the difference is hard to see. Videos larger than Full HD are also scaled down to 1920 × 1080.