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Asset Compressor

Convert WebM to MP4

WebM files from screen recorders and browsers often won’t open in editors, on iPhones or in PowerPoint. Convert them to universally compatible MP4 in your browser.

  • No upload
  • No watermark
  • No file size limit
  • Hardware accelerated

Drop videos here to convert them

MP4, MOV, WebM, MKV, AVI and more · no size limit or watermark

Processed on your device. Your videos are never uploaded.

Output format

MP4 with H.264 plays on every phone, computer, TV and social network.

Compression

Balanced usually cuts phone videos by 60–80% with no visible difference on a phone or laptop screen.

Resolution
Exact size & social formats

Applies to the shorter side, so 720p works for landscape and vertical videos. Smaller videos are never enlarged.

Advanced: codec, frame rate, audio, trim
Video codec

Auto picks the most compatible codec your browser can encode. H.265 and AV1 are smaller but play on fewer devices.

Frame rate
Audio
Trim

Use m:ss or seconds. Applies to every video in the list.

How to convert WebM to MP4

  1. 1

    Add your WebM files

    Drop in one or several .webm videos – screen recordings, browser downloads or exported clips.

  2. 2

    Keep the defaults

    The output is MP4 with H.264 video and AAC audio, re-encoded at high quality for the widest compatibility.

  3. 3

    Convert

    Hardware encoding keeps it quick; the progress bar shows the time remaining.

  4. 4

    Download

    Save each MP4 or download everything as a ZIP.

Why WebM files don’t open everywhere

WebM uses the VP8, VP9 or AV1 video codecs and Opus audio. Browsers love it, but many desktop apps, video editors, presentation software and older phones expect MP4 with H.264. Converting once solves it for good.

Re-encoded to H.264 for maximum compatibility

MP4 can technically hold VP9 video, but many players still refuse it. That’s why this tool re-encodes to H.264 – the most widely supported codec in the world – at a high quality setting, while the Opus audio becomes AAC.

Want a smaller file at the same time? Choose Balanced or Small quality before converting.

Screen recordings and meetings

Many screen recorders and meeting tools save WebM. Screen content with sharp text compresses very well in H.264, so converted recordings are often smaller than the original while text stays crisp.

Making videos smaller while converting

Screen recordings are often recorded at high bitrates. Choosing Balanced quality or a lower resolution such as 1080p or 720p in the settings converts and compresses in one pass, which is handy before emailing a recording or attaching it to a ticket.

Frequently asked questions

Does converting WebM to MP4 lose quality?

The video is re-encoded, but at the default high quality the difference is not visible in normal playback.

Is transparency in WebM videos kept?

No. MP4 with H.264 has no transparency, so transparent areas become black. Keep WebM if you need an alpha channel.

How long does it take?

With hardware encoding, usually less than the length of the video itself. Older browsers use a slower compatibility mode.

Is my recording uploaded?

No. The conversion runs in your browser; your file never leaves your device.

Can I convert WebM on an iPhone?

Yes, in Safari on iOS 16.4 or newer. Select the WebM file from the Files app and download the MP4 when it’s ready.

Related tools

MP4 to WebM

WebM with VP9 or AV1 is built for the web: smaller files at the same visual quality, supported by every modern browser. Convert your MP4s locally.

Video converter

Change a video’s format in seconds. When the codecs allow it, the streams are copied without re-encoding, so the quality stays exactly the same.

Compress video

Shrink MP4, MOV, WebM and MKV files on your own device with hardware-accelerated encoding. Choose a quality level or an exact target size – no upload, no watermark.

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