Convert MP4 to WebM
Re-encode MP4 files as WebM (VP9 + Opus) for websites that want the modern format. Runs in your browser.
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This MP4 to WebM converter re-encodes standard videos as WebM (VP9 + Opus) — the compact, royalty-free format built for the web. The conversion runs in your browser.
WebM files are typically smaller than MP4 at the same visual quality, which is why modern websites prefer them.
Why Use This MP4 to WebM Tool?
- Web-optimized output — VP9 + Opus in a WebM container
- Usually smaller than MP4 at equal visual quality
- Feature-detected — the tool only offers WebM if your browser can encode it
- Private — converted in your browser, no upload
- Free, no signup
How to Convert MP4 to WebM — 3 Steps
- Drop your MP4 into the box above, or tap the box to pick it from your device.
- WebM output is pre-selected — the page only lists formats your browser can encode.
- Press the blue Convert button and download the WebM when the bar completes.
WebM: the Format Websites Ask For
WebM carries VP9 (or VP8/AV1) video and Opus audio in an open container — no licensing questions, efficient compression, and first-class support in every browser. When a website, design system or docs platform asks for WebM, it is asking for smaller files and cleaner licensing, and delivering MP4 there wastes bandwidth on every view.
The conversion decodes your MP4 (H.264 video, AAC audio) and re-encodes it with your browser's VP9 encoder. VP9 encodes more slowly than H.264 — that is the trade for its compression — so expect the job to take longer than an MP4-to-MP4 pass, with real progress on the bar throughout. The payoff is measured at the end: WebM files commonly land 20–40% smaller than the MP4 equivalent.
Where WebM works: every modern browser, HTML5 video elements, most modern CMS and design tools. Where it does not: some older desktop applications and devices — keep the MP4 original as the shareable copy and use WebM where the web is the destination.
Everything runs in your browser with nothing uploaded. If your browser cannot encode VP9, the tool says so up front instead of producing a broken file — Chrome and Edge handle it.
Frequently Asked Questions
VP9 encoding is more computationally heavy than H.264 — that is the trade for its better compression. The progress bar tracks the real encode.
Usually 20–40% smaller at equal visual quality, depending on content.
Every modern browser, HTML5 video players, and most modern CMS and design tools. For maximum-compatibility sharing, keep the MP4.
Your browser cannot encode VP9/VP8. Chrome and Edge can; some Safari versions cannot.
Yes — audio becomes Opus in the WebM container, the standard web pairing.
No — the conversion runs entirely in your browser.
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