How to convert MP4 to WebM
- 1
Drop your MP4 file into the converter above, or click to browse. Nothing is uploaded — the file stays on your device.
- 2
Adjust the settings (quality, resolution, and trim). Tip: For background/hero videos on websites, drop the resolution to 720p — it dramatically cuts the file size visitors have to download.
- 3
Click “Convert to WebM”. The conversion runs locally in your browser — larger files take longer, and a progress bar keeps you posted.
- 4
Preview the result and hit Download to save your WebM file.
Why convert MP4 to WebM?
WebM is the web's royalty-free video format, preferred where licensing or open standards matter — some publishing platforms, wikis, and open-source projects accept only WebM. It also pairs naturally with the HTML5 <video> element across every modern browser.
This converter encodes VP8 video with Opus audio, the classic WebM combination with the broadest playback support. You control quality and resolution, so you can produce a lightweight web-ready version of any MP4.
MP4 vs WebM at a glance
| MP4 | WebM | |
|---|---|---|
| Type | Video container (H.264 + AAC) | Video container (VP8/VP9 + Opus) |
| Compression | Lossy, very efficient | Lossy, efficient, royalty-free |
| Audio | Yes (AAC) | Yes (Opus/Vorbis) |
| Compatibility | Universal — every device, browser, and editor | All modern browsers; weak in editors and on Apple devices |
| Best for | Sharing, social media, editing, playback anywhere | Web embeds, HTML5 video, screen recordings |
About the formats
MP4 MPEG-4 Part 14
MP4 is the most widely supported video format in the world. Built on the H.264 codec with AAC audio, it plays on every phone, browser, TV, and editing app, and offers an excellent balance of quality and file size. When in doubt, MP4 is the safe choice for sharing video.
WebM WebM (VP8/VP9 + Opus)
WebM is the open, royalty-free video format built for the web, using the VP8/VP9 codecs with Opus or Vorbis audio. Browsers and screen recorders love it — Chrome extensions and many capture tools export WebM by default — but desktop editors, iPhones, and smart TVs often refuse to open it.
Frequently asked questions
Which codec does the WebM use — VP8 or VP9?
VP8 with Opus audio. VP8 encodes several times faster in the browser than VP9 and plays everywhere WebM is supported. If you need VP9's extra compression for very large-scale delivery, a desktop FFmpeg is the better tool.
Why use WebM instead of MP4 on a website?
WebM is royalty-free (no H.264 licensing questions), often compresses slightly better at web resolutions, and is required by platforms like Wikimedia that only accept open formats. For general sharing, though, MP4 remains more compatible.
Is this MP4 to WebM converter really free?
Yes — completely free, with no watermarks, no sign-up, and no conversion limits. The tool is supported by ads on this page, so the converter itself never asks you for anything.
Are my files uploaded to a server?
No. This converter runs entirely in your browser using WebAssembly (a browser build of FFmpeg). Your MP4 file never leaves your device — nothing is uploaded, stored, or seen by us, which also makes it safe for private or confidential files.
Is there a file size limit?
There's no hard limit. Because conversion happens on your own device, the practical ceiling is your browser's memory — files up to a few hundred megabytes work well on most computers. Very large files may be slow or fail on low-memory devices.
Why does the first conversion take a moment to start?
The first time you convert, your browser downloads the conversion engine (about 31 MB) once. It's cached after that, so later conversions start instantly — and they keep working even offline.
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