Browser edition: files stay on your device. Up to 100 MB total and 10 minutes. First use downloads a 32 MB engine. Some formats depend on codec support. Public-link downloading is not ready on this free deployment.
Convert MP4 to WMV
Convert MP4 to WMV online for free. Smart remux when possible, high-quality encoding when not.
How to convert MP4 to WMV
- Add your fileDrop it on the page, choose it from your device, or paste it with Ctrl+V.
- ConvertAdjust settings if you like, then press the button. You'll see live progress.
- Browser processing uses original files on your device. Public-link downloading is unavailable.
What happens to your file
MP4 files are common for sharing, uploading to social networks, playing on any device, but not every app or device opens them. WMV is the better choice for legacy Windows software and presentations. Spool converts MP4 to WMV with FFmpeg — real decoding and encoding, not a renamed file extension.
A real re-encode. MP4 usually contains H.264 or H.265 video with AAC audio, which WMV players can't decode, so Spool re-encodes to WMV2 video and WMA audio. "Balanced" is visually indistinguishable from the source for most videos; "High" uses a lower CRF for archiving; "Smaller file" trades a little sharpness for a much smaller file.
Settings
- Quality — High, Balanced, Smaller file. Balanced keeps the original streams when possible (no quality loss, very fast).
- Resolution — Same as source, 4K (2160p), 1440p, 1080p, 720p, 480p, 360p, 240p
- Audio bitrate — Auto · keep original if possible, 320 kbps · best, 256 kbps, 192 kbps · standard, 128 kbps · small, 96 kbps, 64 kbps · voice
MP4 vs WMV
| MP4 | WMV | |
|---|---|---|
| Full name | MPEG-4 Part 14 | Windows Media Video |
| Created by | ISO / MPEG, 2001 | Microsoft, 1999 |
| Type | Video container | Video container |
| Typical contents | H.264 or H.265 video with AAC audio | WMV video with WMA audio |
| Best for | sharing, uploading to social networks, playing on any device | legacy Windows software and presentations |
| Strength | Plays everywhere, including iPhone, Android, Windows and macOS | Works in old versions of PowerPoint and Windows Media Player |
| Weakness | Lossy: every re-encode loses a little quality | Poor support on Mac, iPhone and Android |
About MP4
- Type
- MPEG-4 Part 14
- Contains
- H.264 or H.265 video with AAC audio
- Use
- sharing, uploading to social networks, playing on any device
About WMV
- Type
- Windows Media Video
- Contains
- WMV video with WMA audio
- Use
- legacy Windows software and presentations
FAQ
Will converting MP4 to WMV reduce quality?
A small amount, because the video has to be re-encoded. With the default "Balanced" setting (H.264 CRF 23) the difference is not visible for most videos; choose "High" to minimize it.
How long does it take?
Re-encoding runs at roughly real-time or faster for 1080p video. You'll see live progress and the time remaining.
Can I convert several MP4 files at once?
Yes. Drop up to 10 files at a time — each one is converted in parallel and you can download them individually or all at once.
Is there a file size limit?
Convert and edit files on your device. The browser edition accepts up to 100 MB total, media up to 10 minutes and video up to 4K. Codec availability and device memory can limit individual jobs.
Is this MP4 to WMV converter free and safe?
Yes. There are no pop-ups, redirects or fake download buttons, and no software to install. Files are transferred over HTTPS, processed in isolated job folders and deleted automatically.