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MP4 to WebM Converter — Free, No Upload, No Watermark

Convert MP4 to WebM online: make a WebM for web pages, with VP8 video and Vorbis sound. Free, no upload, runs in your browser.

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Drop a file here or click to browseMP4 files — converted on your device, never uploaded🔒 Processed on your device — never uploaded

A video that can be copied across without re-encoding keeps its original quality, whatever you choose here.

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Convert MP4 to WebM without uploading your video

WebM is the open, royalty-free video format that every current browser plays, which makes it a natural choice for a video on your own web page or for a project that avoids patent-encumbered formats. This converter turns an MP4 into a WebM with VP8 video and Vorbis sound.

When WebM is the right choice

Use WebM for a video you embed in your own site, for tools and platforms that ask for it, and in open-source projects. For sending a video to a person, MP4 is still the safer choice because phones, editors and messaging apps handle it better. Many sites offer both, with WebM first and MP4 as the fallback.

What the conversion does

The picture is re-encoded to VP8 and the sound to Vorbis, both fast encoders in the browser. Transparency is flattened, because VP8 cannot store it. A higher quality setting means a larger file: Balanced aims for about 2 Mb/s of picture, High about 4 Mb/s, and Small about 1 Mb/s.

File size and speed

A WebM made this way is usually a similar size to the MP4 it came from, and sometimes larger, since VP8 is an older design than the H.264 used in most MP4s. Re-encoding takes time in proportion to the length of the video, so a short clip is quick, and cutting a long video first with the video trimmer saves waiting.

How this converter works

Converting to WebM re-encodes the video: the picture becomes VP8 and the sound becomes Vorbis, the combination that browsers play. A higher quality setting keeps more detail and makes a bigger file.

Frequently asked questions

How do I convert MP4 to WebM?
Drop your MP4 file into the box above, or click to choose it, pick a quality and press Convert to WebM. When it finishes, press Download. The conversion runs in your browser, so the video stays on your device.
Is my video uploaded when I convert it?
No. The conversion runs inside your browser with a WebAssembly build of FFmpeg, and only the engine itself, about 31 MB, is downloaded, once. Your MP4 file never leaves your device, and there is no watermark and no account.
Will converting MP4 to WebM reduce the quality?
A little. The picture has to be re-encoded into WebM's own codec, once, and any re-encode loses a small amount of detail. Choose High for the closest match and Small if file size matters more.
What is a MP4 file?
MP4 is the most widely supported video container. It usually holds H.264 (sometimes HEVC) video with AAC sound, and it plays on practically every phone, computer, TV and browser, which makes it the safe default for sharing and uploading.
What is WebM?
WebM is an open, royalty-free format designed for the web. It holds VP8, VP9 or AV1 video with Vorbis or Opus sound, and it plays in all current browsers, but many editors, phones and older Apple software handle it badly or not at all.
Why is my WebM bigger than the MP4?
VP8, the video codec used here, is less efficient than the H.264 in most MP4 files, so it needs more data for the same quality. Choose Small to make the WebM smaller, at some cost in detail.
Does the WebM work on iPhones?
Support varies. Recent versions of Safari play WebM, but older Apple software does not, and some apps will not open it. For a video that must play on every iPhone, MP4 is the safer choice.

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