Convert MP4 to WebM — Free Web Video Converter
Convert MP4 videos to WebM format. Perfect for web embedding and HTML5 video. Free online converter.
Conversion settings — add a file to adjust
About MP4 files
MP4 with H.264 is the common video format. WebM is the open web format built around VP9 video and Opus sound, and browsers play it natively.
Web developers convert MP4 to WebM for background videos and HTML5 players, and some sites and apps prefer WebM uploads. VP9 gives good quality per bit on the web.
How we convert MP4 to WebM
- Video
- VP9 in constant quality mode at CRF 31, with multi-threaded encoding at the good-quality speed setting.
- Audio
- Opus at 192 kbps.
- Resolution
- Kept from the MP4 unless you choose a smaller size.
- Measured
- A 30-second 1080p MP4 of 23.7 MB became a 27.8 MB WebM in about 38 seconds.
Common problems and fixes
The WebM is not smaller than the MP4.
At our default quality VP9 keeps a lot of detail. Choose the Low preset or a lower resolution for a smaller web file.
The conversion takes longer than MP4 to MOV.
WebM always needs a full VP9 encode, which is slower than copying streams. Trim the clip if you only need a part.
The video will not play on an older iPhone.
Older iPhones have limited WebM support. Keep the MP4 as a fallback source in your web page.
About MP4 to WebM Conversion
WebM is the web's native video format, designed by Google specifically for HTML5 video delivery. While MP4 works well on most platforms, WebM offers royalty-free encoding and often achieves smaller file sizes at equivalent quality—valuable for website optimization and cross-browser video.
Our MP4 to WebM converter transforms your videos using VP9 encoding for maximum compression efficiency. The result is web-optimized video files that load faster and consume less bandwidth while maintaining excellent visual quality.
Why Convert MP4 to WebM?
Web performance benefits from WebM. The format typically produces 20-30% smaller files than MP4 at equivalent quality. For websites serving video content, this means faster loading, reduced bandwidth costs, and better user experience on mobile networks.
Browser optimization favors native formats. While modern browsers play both MP4 and WebM, some browsers handle WebM more efficiently. Providing WebM alongside MP4 ensures optimal playback across all browsers.
Open source and licensing considerations matter for some projects. WebM is completely royalty-free; H.264 (in MP4) involves patent licensing. For projects with licensing concerns, WebM avoids potential complications.
Common Use Cases
- Optimize website video for faster loading