Convert WMV to MP4 Online — No Upload, No Watermark
WMV is Microsoft’s Windows Media container — unsupported on macOS and iOS without extra software. Converting to MP4 gives you a file that plays on every phone, browser, and editor without re-encoding at playback time.
Drag & drop your video here, or click to browse
Max file size: ~2 GB (memory permitting)
Where WMV files come from
WMV is Microsoft's own format, produced by Windows Movie Maker, old Windows screen recorders, and corporate training or e-learning tools that standardised on it in the 2000s. Most surviving WMV files are archived business video or old family footage.
What changes when you convert WMV to MP4
| Container | Rewritten to MP4 with the moov atom at the front, so it starts playing before it finishes downloading |
|---|---|
| Video | Re-encoded to H.264 at CRF 23, which is visually lossless for most footage |
| Audio | Re-encoded to AAC, the codec MP4 players expect |
Worth knowing first
WMV is the one format here that has essentially no support outside Windows. macOS dropped it when QuickTime lost its Windows Media components, and no browser or phone has ever decoded it. If a WMV will not open on a Mac or an iPhone, converting is the only practical fix, since there is no plugin left to install.
FAQ
Why will WMV not play on my Mac?
Apple removed Windows Media support from QuickTime long ago and never replaced it. There is no current plugin worth installing. Converting to MP4 is the realistic route, and the file will then also work on your phone and in any browser.
Some WMV files are protected. Will those convert?
No. WMV files that carry Windows Media DRM, which was common for purchased or rented video, cannot be decoded without the licence. The conversion will fail on those. Files you recorded or exported yourself have no DRM and convert normally.
Does the quality hold up?
Yes, within the limits of the source. WMV files are usually low-bitrate to begin with, and the conversion will not add detail that was never recorded. What it does is stop a second generation of loss being visible, by encoding at CRF 23 rather than matching the original low bitrate.
Is this WMV to MP4 converter really free and without upload?
Yes. The tool runs entirely in your browser using FFmpeg compiled to WebAssembly. Your WMV file never leaves your device — open the DevTools Network tab to verify zero uploads. No signup and no watermark. The practical size limit is the memory your browser gives this tab, which is generous on a computer and a few hundred megabytes on a phone.