MP4 to WebM converter
Smaller video files built for the web.
Runs in your browser. Your files never leave your device.
- VP9 and Opus output
- Batch convert
- Nothing uploaded
How to convert MP4 to WebM
- Drop your MP4 files here.
- Each one converts to WebM.
- Download the WebM files.
Why WebM files are often smaller
VP9, the video codec WebM uses here, generally needs a lower bitrate than H.264 to reach a comparable picture quality. For video that will sit on a web page and get loaded by many visitors, that smaller file means faster page loads, at the cost of more processing time to encode it in the first place.
Where WebM works and where it doesn't
| Works well | |
|---|---|
| Your own website or app | Yes, with an MP4 fallback for older Safari |
| Uploading to social platforms | Not usually, they expect MP4 |
| Sharing directly with someone | Only if you know their device plays WebM |
Using the HTML5 video tag
If you're embedding the result with a plain <video> element, list the WebM file first and keep an MP4 copy as a fallback source. Browsers pick the first source they can play, so visitors on Chrome, Firefox or Edge get the smaller WebM automatically, while older Safari versions fall back to the MP4.
MP4 to WebM FAQ
Why convert MP4 to WebM?
WebM with VP9 often produces smaller files than H.264 MP4 at a similar quality, which helps pages load faster, and it's the format expected by some video embedding tools.
Do all browsers play WebM?
Chrome, Firefox and Edge play WebM natively. Safari support depends on the version, so keep an MP4 copy if you need it to work everywhere, especially on older iPhones or iPads.
Does this take longer than other conversions?
Encoding VP9 video takes more processing than encoding H.264, so large or high resolution files take noticeably longer than converting the same file to MP4.
What happens to the audio?
AAC audio is re-encoded to Opus, WebM's native audio codec.
Is WebM good for uploading to social media?
Most social platforms expect MP4 for uploads. Use WebM for your own website or app, and keep MP4 for uploading elsewhere.
Will the video quality look worse after converting?
The tool re-encodes at a fixed high quality setting, so the visible difference should be minimal, but any lossy re-encode is technically a small step down from the original, especially if you convert the same file back and forth more than once.
Are my videos uploaded?
No. Everything runs on your device.