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Home » Video Tools » MP4 to WebM Converter

MP4 to WebM Converter

Convert MP4 videos to WebM for websites and HTML5 players. WebM (VP8 video + Opus audio) is open, royalty-free and supported by all modern browsers. The settings are ready: pick a quality and click Convert.

🔒 Your video is processed locally in your browser. Your file is never uploaded.

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How to use it

  1. Choose a video (or drop it on the box). The format and length are detected automatically.
  2. Pick the output format, quality and resolution.
  3. Click "Convert", wait for the progress bar and download the result.

When to use WebM instead of MP4

Use WebM for videos you embed on your own website, especially muted background loops, because every modern browser plays it with the open VP8/VP9 codecs. Keep MP4 for anything you share with people or upload to social networks: iPhones, WhatsApp and most editors expect MP4.

For the best result on a website, provide both: <video><source src="clip.webm" type="video/webm"><source src="clip.mp4" type="video/mp4"></video>. Browsers pick the first format they support. For a background video, 720p at "Medium" quality and no sound usually looks great at a few MB.

MP4 (H.264)WebM (VP8/VP9)
BrowsersAllAll modern (Safari 14.1+)
iPhone / WhatsApp / editorsYesLimited
LicensingPatented codecOpen, royalty-free
Best forSharing & uploadingEmbedding on websites

Frequently Asked Questions (FAQ)

Q: Is my file uploaded to a server?
A: No. The tool runs FFmpeg compiled to WebAssembly inside your browser tab. Your file is read directly from your device and the result is created locally. Only the video engine itself (open-source ffmpeg.wasm, about 10 MB compressed) is downloaded the first time, from a public CDN; after that it is cached.
Q: How big can the file be?
A: Up to about 500 MB works well on a computer and about 150 MB on a phone. Larger files may still work but can be slow or run out of browser memory. Trimming the clip or lowering the resolution first helps.
Q: Why is it slower than a desktop app?
A: The browser version of FFmpeg runs on a single CPU core and without hardware acceleration. A 1-minute 1080p re-encode typically takes 1–3 minutes. When possible the tools copy the streams without re-encoding, which takes only seconds.
Q: Why does converting to WebM take longer than to MP4?
A: WebM always needs a full re-encode with the VP8 codec, which is slower in a browser than copying H.264 streams. Choosing 720p or 480p speeds it up a lot.