Convert MP4 to WEBM
Convert MP4 to WEBM free in your browser. No upload, no signup, no watermark. Files stay on your device.
drop a .mp4 file
or click to browse
max 500 MBrelated
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how to convert mp4 to webm
Drop your MP4 file
Drag your MP4 file into the drop zone above, or click the box to pick a file from your computer or phone. The browser reads the file directly — nothing uploads.
Click Convert
The page runs ffmpeg.wasm on your device to decode the MPEG-4 Part 14 and encode it as WebM. Most conversions finish in a few seconds; large or codec-heavy files (RAW, video) can take longer.
Download the WEBM file
When the conversion finishes, the WEBM file is ready to download. Save it anywhere on your device.
FAQ
common questions
Why convert MP4 to WebM?
Three main reasons: (a) you're publishing video to a website and want smaller file sizes than MP4 typically achieves; (b) the receiving platform prefers WebM (some open-source video players, certain CMSes); (c) you want a royalty-free format. For arbitrary distribution and broadest compatibility, MP4 is still the safer choice — WebM doesn't play natively on iOS Safari historically, on older smart TVs, or on many game consoles.
Will the WebM be smaller than the MP4?
Usually somewhat — WebM uses VP9 or AV1 codecs which compress slightly better than MP4's H.264. Expect 10–30% smaller files at comparable visible quality. If your MP4 already uses H.265 (HEVC), the size difference is smaller; if it uses older H.264, WebM saves more.
Will the video quality match?
Close but not identical. Both formats are lossy at the codec level, so converting MP4 to WebM is decode-then-re-encode — a second generation of compression on top of whatever was already in the MP4. The visible difference is minor at sensible quality settings; not noticeable in casual viewing.
Will audio survive the conversion?
Yes — WebM containers carry audio (typically Opus or Vorbis codec). The converter re-encodes your MP4's audio track to a WebM-compatible codec. Quality is preserved at near-original fidelity for typical content; the conversion adds a small generational loss similar to the video side.
Will WebM play on every device the MP4 does?
No — that's the trade-off. WebM is supported by Chrome, Firefox, Edge, Android, and modern Safari, but historical iOS Safari, some smart TVs, game consoles, and older Windows builds don't open WebM natively. For browser-only delivery, WebM is great; for downloadable content meant to play anywhere, MP4 remains the safer choice.