MP4 to WebM Converter
Convert MP4 to smaller, royalty-free WebM for faster-loading web video, free and entirely in your browser.
What is MP4?
MP4 with H.264 is the universal video format, but it isn’t the most efficient — H.264 needs a higher bitrate than newer codecs to hit the same visual quality, and MP4 carries licensing overhead that some open-web projects want to avoid.
Why convert MP4 to WebM?
WebM (VP9/AV1) compresses noticeably smaller than H.264 MP4 at equivalent quality and is royalty-free, which is why it’s the format of choice for fast-loading website background video, HTML5 `<video>` elements, and open-source projects. Converting MP4 to WebM is the usual move when optimizing a video for web page load speed.
How to convert MP4 to WebM
- Drop your MP4 file. Drag and drop a MP4 file, or click to browse. First use loads the ffmpeg.wasm engine (~31 MB, cached in your browser after).
- Confirm output is WebM. This page pre-selects WebM as the output format — change it in the format picker if you’d rather export something else.
- Set quality and convert. Pick a quality or bitrate preset, then click Convert. Processing runs locally on your device and typically finishes in well under a minute for short files.
- Download. Click Download to save your WebM file. Nothing was ever uploaded to a server.
Your file never leaves your browser — conversion runs locally via ffmpeg.wasm, not on a server.
Use Cases
- Shrink a hero/background video for faster website load times
- Publish video on an open-source project page without codec licensing concerns
- Serve a smaller `<video>` file to visitors on slow connections