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WebMMP4

Convert WebM to MP4

This free WebM to MP4 converter changes your WebM (.webm) file into a MPEG-4 Part 14 (.mp4) file, right in your browser. There is nothing to install, no account to create, and no limit on how many files you convert.

100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

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The conversion runs on your own device using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is never uploaded to a server. MP4 is best for sharing and playing almost anywhere, which is the usual reason to convert from WebM.

Why convert WebM to MP4?

  • MP4 plays on more devices and apps than WebM, so it is the safer choice for sharing.
  • The video is re-encoded to efficient H.264, so the MP4 file is usually about the same size as your WebM.
  • Pick MP4 when you need a file made for sharing and playing almost anywhere.

WebM vs MP4

PropertyWebMMP4
Full nameWebMMPEG-4 Part 14
ContainerWebMMPEG-4
Typical codecVP9 / VP8 + OpusH.264 + AAC
CompatibilityWideUniversal
Relative sizeSmallestSmall
Best forFast-loading web and HTML5 videoSharing and playing almost anywhere

How to convert WebM to MP4

  1. Add your WebM file

    Drag and drop your .webm file onto the upload area, or click to browse and pick it from your device.

  2. Start the conversion

    Click "Convert to MP4". Everything runs locally with ffmpeg compiled to WebAssembly (ffmpeg.wasm) - your file stays on your device.

  3. Wait a few seconds

    A progress bar shows the conversion. The first run is slightly slower while the engine loads, then it is cached.

  4. Download your MP4 file

    When it finishes, download the .mp4 file straight to your device.

Frequently asked questions

Is this WebM to MP4 converter free?
Yes. It is completely free with no signup, no watermark, and no limit on how many files you convert. It is supported by ads, which keeps the conversion itself free.
Are my files uploaded to a server?
No. The conversion runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm), so your file is processed in memory on your own device and is never uploaded, stored, or seen by anyone.
Will I lose quality converting WebM to MP4?
The video is re-encoded to MP4 with a high-quality setting, so the result looks very close to the original WebM. Re-encoding is never bit-for-bit identical, but the loss is minimal.
Will the file get smaller or larger?
Usually similar. The video is re-encoded to H.264 at a high-quality setting, so the MP4 file is typically about the same size as your WebM; the container itself adds little.
What is the difference between WebM and MP4?
WebM is WebM (a WebM container, typically VP9 / VP8 + Opus); MP4 is MPEG-4 Part 14 (an MPEG-4 container, typically H.264 + AAC). MP4 is best for sharing and playing almost anywhere, while WebM is best for fast-loading web and HTML5 video.
How long does the conversion take?
Most files finish in a few seconds to under a minute, depending on length and your device. The first conversion is a little slower while the engine downloads and caches, then later runs start instantly.

Related conversions

MOV → MP4AVI → MP4MKV → MP4FLV → MP4WMV → MP4M4V → MP4

Need more formats or options? Use the full Change Video Format.