Uwarp

Quality

Balanced is CRF 30. Higher keeps more detail. Smaller uses CRF 40.

MOV, MP4, MKV, AVI, or MPEG. The first run downloads FFmpeg once in this browser.

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Convert a video file to WebM

Convert a MOV, MP4, or MKV file to WebM in your browser. No signup, and the file stays on your device.

What is a WebM converter?

WebM is a video file for the web. This page re-encodes a MOV, MP4, or MKV as that file.

WebM converter features

Save a common video file as WebM.

  • Video to WebM

    Upload MOV, MP4, MKV, AVI, or MPEG and download a .webm file.

  • MOV to WebM

    A QuickTime .mov file is converted with the same encoder as the other formats.

  • Three quality levels

    Balanced uses CRF 30. Higher keeps more detail. Smaller uses CRF 40.

  • Browser-side conversion

    The video stays on your device. No account is required to convert to WebM.

How to convert a video to WebM

Three steps from a video file to a WebM file.

  1. Add the video

    Drop a MOV, MP4, MKV, AVI, or MPEG file.

  2. Choose a quality

    Pick Higher, Balanced, or Smaller, then click Convert to WebM.

  3. Download the WebM

    Save the .webm file and play it in a browser or video player.

Tips for converting to WebM

What this converter writes, and which files it leaves alone.
  • 01

    Use a video file you already have

    Drop a MOV, MP4, or MKV from your device. A web address is not fetched.

  • 02

    Already a WebM

    A file that is already .webm does not need this conversion. WebM to MP4 is the other direction.

  • 03

    Watch the size

    Each video can be up to 200 MB. The first conversion downloads FFmpeg once in this browser.

Good uses for a WebM converter

When a site or player wants a WebM file.

  1. Put a MOV on the web: Turn a QuickTime file into a WebM a browser can play.

  2. Share a smaller clip: The Smaller quality setting uses CRF 40.

  3. Keep picture and sound: The WebM keeps the video and the audio track when the file has one.

Why convert to WebM here

A local conversion to a WebM file.

  • No signup

    Convert a video without an account.

  • Stays on your device

    Encoding runs in the browser.

  • A normal WebM

    The download is VP8 video and Vorbis audio in a .webm file.

Technical details

How this conversion to WebM works.
Input
MOV, MP4, M4V, MKV, AVI, MPEG, or MPG, up to 200 MB.
Output
A WebM file with VP8 video (CRF 20, 30, or 40) and Vorbis audio at 128 kbps when the clip has sound.
What is left out
Subtitle tracks are not copied. A file that is already WebM is left as it is.
Where it runs
FFmpeg encodes the WebM locally in the browser. The file is not uploaded for conversion.

Sources & References

References for the WebM file this converter writes.
  • “It is primarily intended to offer a royalty-free alternative to use in HTML video and HTML audio elements.”
    — Wikipedia — WebM

    WebM: The download is that video file, with a .webm extension. en.wikipedia.org/wiki/WebM

  • “WebM was a collaborative effort first released in 2010.”
    — Wikipedia — WebM

    WebM release: This tool writes that WebM container, with VP8 video inside it. en.wikipedia.org/wiki/WebM

Frequently Asked Questions

Quick answers about this tool—open a question to read more.