Will this mp4 to webm converter lose quality?

A little, unavoidably. Re-encoding is lossy: some detail is discarded to shrink the file. At normal viewing sizes the difference is usually hard to spot.

Where does WebM play?

In current Chrome, Firefox and Edge, and in recent Safari. Very old players and some editors do not accept WebM — keep the MP4 for those.

Will my file definitely get smaller?

Usually, but not guaranteed. A video that is already heavily compressed, or very short, may shrink little or not at all.

Yes. Audio is re-encoded as Opus, the standard WebM audio codec, and stays in sync with the picture.

Is this mp4 to webm converter free?

Yes. It runs entirely in your browser — no account, no signup, and nothing uploaded.

MP4 to WebM Converter – Smaller Files for the Web

WebM is the open video format built for the web. It pairs VP9 video with Vorbis or Opus audio in a light container, so files are noticeably smaller than MP4 at similar quality. This free mp4 to webm converter does the conversion in your browser, so nothing is uploaded and no signup is needed. A WebM copy of your video is ideal for embedding on a page or sending where every megabyte counts. The honest limits: WebM plays in all modern browsers, but some older desktop players and editors still expect MP4.

How to use this mp4 to webm converter

From a MP4 file to a WebM file, without uploading anything.

1Drop in your MP4 file

Choose a .mp4 file from your device, or drag it onto the tool.

2Let it encode in the browser

Your video is converted locally with VP9 video and Vorbis audio, so it never leaves your device.

3Download the WebM file

The converted file downloads with the same base name and the new extension, ready to use.

Why convert MP4 to WebM

WebM is the open video format built for the web. It pairs VP9 video with Vorbis or Opus audio in a light container, so files are noticeably smaller than MP4 at similar quality.

The right format for the job

WebM is the open video format built for the web. It pairs VP9 video with Vorbis or Opus audio in a light container, so files are noticeably smaller than MP4 at similar quality.

What WebM gives you

Smaller files that load faster on pages and cost less bandwidth, with quality that holds up next to the MP4 original.

Watch out for this

WebM plays in all modern browsers, but some older desktop players and editors still expect MP4.

Private by design

Decoding and encoding happen on your own device, so personal videos and unpublished work never leave your browser.

MP4 to WebM Converter FAQs

Short, direct answers to the questions readers ask most.

Yes, at similar quality. VP9 encoding keeps the picture close to the MP4 original while the file gets noticeably smaller.

MP4 is the most widely supported video container, pairing H.264 video with AAC audio for broad compatibility.

WebM is the open video format built for the web. It pairs VP9 video with Vorbis or Opus audio in a light container, so files are noticeably smaller than MP4 at similar quality.

WebM plays in all modern browsers, but some older desktop players and editors still expect MP4.

Yes. It runs entirely in your browser, with no account, no signup, and nothing uploaded.