MP4 to WebM converter

Convert MP4 video to WebM in your browser. When the codec fits, only the container changes, so it takes seconds and the quality stays the same.

    Drop MP4 files here or choose files.

    • 500MB per file. Up to 10 minutes when only the container changes, 3 minutes when re-encoding. Up to 5 files at a time
    • The first time you use it, the browser downloads the video engine (about 31MB)

    Auto skips re-encoding when the source can go into the new format as is, which is fast and keeps the quality intact. Otherwise it re-encodes at normal quality. Light reduces the file size at some cost in picture quality.

    For vertical video this refers to the shorter side. Choosing a size smaller than the original forces a slower re-encode. The tool never upscales.

    Files never leave this device. Privacy policy

    Result

    Upload a MP4 video and click Convert. The WebM file will appear here.

    What to do next

    WebM to MP4 converter

    Convert a WebM video back to MP4.

    Compress a video

    Shrink the video to fit iMessage, Gmail or Discord upload limits.

    Trim a video

    If a video is too long to convert, cut out the part you need first. Quality stays the same.

    How it works

    Choose a MP4 video and click Convert to save it as WebM. WebM is built for playback in a browser, on web pages or in Discord. The video is VP8 and the audio is Vorbis.

    With quality set to Auto, the tool first checks the codec inside the video. If WebM can hold it as is, it swaps only the container without re-encoding. That takes a few seconds and the quality is unchanged. If the codec does not fit, the tool re-encodes and tells you below the result which method it used. Several files convert one after another.

    Things to know

    Converting to WebM almost always means re-encoding, so the limit is 3 minutes. At Normal quality, the difference is hard to see on a phone screen.

    Re-encoding processes every frame on your device, so it is slow. That is why the limit is 10 minutes when only the container changes and 3 minutes when re-encoding. 4K video is reduced to 1080p when it has to be re-encoded.

    Frequently asked questions

    Are all MP4 files the same?

    MP4 is the name of the container. The video inside is usually H.264, or H.265 on iPhones and newer cameras. This tool checks the codec first, and if the new container can hold it as is, it does not re-encode.

    Where does WebM play?

    Chrome, Edge, Firefox and current Safari play it, and it embeds well in web pages. Some apps cannot open it, including the iPhone Photos app, the built-in Windows apps and some video editors, so for sharing or editing, MP4 is the safer choice.

    Why does it take so long? Does it work on a phone?

    The video is processed on your device, not on a server. When only the container changes, it takes a few seconds. When the video has to be re-encoded, it can take several times the length of the video depending on your hardware. It works on a phone but much more slowly, and it stops if the screen turns off or you switch apps. For long videos, use Chrome or Edge on a computer.

    Are my files uploaded to a server?

    No. The conversion runs entirely in this browser, and the file never leaves your device. The only download is the conversion engine, once. The result disappears when you close the page, so use the save button to keep it.

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