MP4 to WebM Converter – Free Online

Video & Audio Converter

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How to Convert MP4 to WebM Online

Upload your MP4 file

Drag and drop your .mp4 file onto the page or click to browse. You can select several MP4 files at once to batch-convert them.

WebM is preselected

The output format is already set to WebM, so you can convert immediately. If you need to, adjust the codec, resolution, frame rate or bitrate in the settings panel first.

Convert and download

Click Convert. The WebM file is processed on your own device; nothing is uploaded to a server. When it finishes, click Download to save it (or Download all to get a batch as a ZIP).

Why Convert MP4 to WebM?

WebM with VP9 video typically achieves the same quality as H.264 MP4 at 20 to 40% smaller files, which is why YouTube and most modern websites serve it. Converting MP4 to WebM lets you offer a faster-loading, royalty-free video on your site alongside an MP4 fallback for Safari.

Choose VP9 for the best compression or VP8 for the widest compatibility with older browsers. The audio is encoded to Opus, and the entire conversion runs locally in your browser.

Private by design: your MP4 file is converted on your own device and never uploaded.
WebM preselected: the output format is already chosen, so it is a one-click conversion.
Batch friendly: convert several MP4 files in one go and download them as a ZIP.
No limits, no watermark: free for files of any size, with nothing stamped on the output.

MP4 vs WebM

MP4 (MPEG-4 Part 14): MP4 is the most widely supported video container in the world. It usually carries H.264 or H.265 video with AAC audio, plays on every phone, browser, TV and editing app, and is the safest choice for sharing. It is best for sharing, social media, web playback and mobile devices.

WebM (WebM): WebM is the open, royalty-free container built for the web. It pairs VP8, VP9 or AV1 video with Opus or Vorbis audio and streams natively in Chrome, Firefox, Edge and HTML5 players. It is best for HTML5 video, websites and open-source projects.

In short: keep MP4 when the priority is sharing, social media, web playback and mobile devices, and switch to WebM when the file is headed for HTML5 video, websites and open-source projects. Need a different target? The full Video Converter supports every format listed below.

MP4 to WebM FAQ

Does Safari play WebM?

Safari 14.1 and later on macOS play WebM, but iOS support is limited. Serve WebM first with an MP4 fallback in your video element for full coverage.

VP8 or VP9?

VP9 produces smaller, better-looking files and is supported by every current browser. Use VP8 only if you must support very old Android or browser versions.

Is this MP4 to WebM converter free?

Yes. Converting MP4 to WebM on MediaConverter.io is completely free, with no watermark, no sign-up and no daily conversion limit.

Are my MP4 files uploaded to a server?

No. The converter runs inside your browser using WebAssembly and WebCodecs, so your .mp4 file is read and converted on your own device. Nothing is uploaded, which keeps private recordings private and means there is no waiting in an upload queue.

Is there a file size limit for MP4 to WebM?

No fixed limit. Because processing happens locally, the practical limit is your computer's memory and patience; multi-gigabyte MP4 files convert fine on a desktop browser. Very large files take longer on phones.

Will converting MP4 to WebM reduce quality?

The video is re-encoded into WebM. Keep the source codec, resolution and bitrate (the defaults) and the result is visually the same as your MP4; lowering the bitrate or resolution is what reduces quality, and you control that trade-off in the settings panel.

Which browsers support the MP4 to WebM converter?

Current versions of Chrome, Edge, Firefox and Safari on desktop all work. Chrome and Edge are fastest because they expose hardware-accelerated WebCodecs decoders.