To convert WebM to MP4 on Windows: install Grabbit and activate Pro, open the Converter tab, browse to your .webm file, select MP4 as the output format, and click Add to Queue. Grabbit converts using FFmpeg locally on your PC — no upload, no file size limit. Pro
WebM is an open video format developed by Google, commonly used for web playback (it's the format browsers use for HTML5 video). You'll typically encounter WebM files when you download a video from a website, record your screen in Chrome with a screen recorder, or download content from YouTube via certain tools.
The problem with WebM on Windows is compatibility. Windows Media Player doesn't play WebM natively. Many video editors (Adobe Premiere, DaVinci Resolve) have limited WebM support. Social media platforms often reject WebM uploads. Converting to MP4 (H.264) gives you maximum compatibility with every device, player, and platform.
| Grabbit (local) | Online converters | |
|---|---|---|
| Uploads your video | ✓ No — 100% local | ✗ Your video uploaded to their servers |
| File size limit | ✓ None | ✗ Usually 500 MB–2 GB |
| Speed | ✓ Limited only by your CPU | ✗ Upload + server queue + download |
| Ads | ✓ Zero ads | ✗ Pop-ups and conversion limits |
| Other formats | ✓ ProRes, DNxHR, MKV, MP3, PNG… | ✗ Limited output options |
Grabbit bundles FFmpeg on your PC. No upload, no waiting for a cloud server, no queue. Conversion speed depends only on your CPU.
Large WebM recordings from screen capture can be several GB. Grabbit handles any size since processing runs on your hardware.
Beyond MP4, Grabbit's Converter also outputs MKV, AVI, MOV, ProRes HQ, DNxHR HQ, MP3, WAV, PNG, and WebP — all from the same app.
WebM files often contain screen recordings with personal data. Grabbit converts locally — nothing is transmitted to any external server.
Install Grabbit for Windows and activate a Pro license. Open the Converter tab, select your .webm file, choose MP4 output, and click Add to Queue. Grabbit converts locally with FFmpeg. The Converter requires Pro ($8.99/month or $59.99/year).
No. Grabbit processes files locally on your PC using FFmpeg, so there is no file size restriction. Online converters like Convertio cap at 100 MB on free plans; Grabbit handles multi-GB WebM files without issue.
WebM videos use VP8 or VP9 codecs, while MP4 typically uses H.264. Converting between codecs requires re-encoding, which means a small quality tradeoff. For typical WebM files (screen recordings, downloaded content), the difference is minimal at the bitrate settings Grabbit uses. For professional workflows requiring lossless output, consider ProRes HQ instead.
Yes. Grabbit's Converter supports multiple output formats: MP4, MKV, AVI, ProRes HQ (.mov), DNxHR HQ, MP3, WAV, PNG, and WebP. Select your preferred output in the format picker.
No. The Converter uses FFmpeg installed locally on your PC. Your WebM files are never uploaded anywhere — conversion runs entirely on your machine.
Windows 10/11 · FFmpeg-powered · 100% local · No upload · $8.99/mo or $59.99/yr