Click to choose a WMV or drop it here
WMV in, MP4 out — converted in your browser, never uploaded. ASF and other video types work too.Video and audio are processed in your browser by FFmpeg (ffmpeg.wasm), free software under the GPL-2.0-or-later and MIT licenses — licenses & source.
About converting WMV to MP4
To convert WMV to MP4, drop your .wmv file on the box above and press Convert to MP4. The page turns the Windows Media video into H.264 video with AAC sound inside an MP4. That is the format every phone, Mac, TV and browser plays.
WMV files are often 10 or 20 years old: clips from Windows Movie Maker, old cameras, school projects, family videos, screen recordings from the Windows XP and Windows 7 days. On a Windows PC they still play. On an iPhone, a Mac, a smart TV or a web page they usually do not.
Everything runs in your browser. Your video is never uploaded.
Features
- WMV in, MP4 out — Windows Media Video 7, 8 and 9 (also VC-1) with WMA sound
- Plays everywhere — H.264 video and AAC sound, the safest MP4 there is
- Three quality levels — High, Good or Smaller file
- Optional resize — 1080p, 720p or 480p for a smaller file
- Preview before you save — play the MP4 on the page, then download it
- Honest result — the page says what it did and shows the size before and after
- Private — no upload, no sign-up, no watermark
What is a WMV file?
WMV stands for Windows Media Video. Microsoft made it in 1999 for Windows Media Player. The video sits in an ASF container (Advanced Systems Format), usually with WMA (Windows Media Audio) sound. The newest version, WMV 9, became the VC-1 standard in 2006, and some old Blu-ray discs use it too.
For about ten years WMV was the normal video file on Windows. Windows Movie Maker saved it, many cameras and screen recorders made it, and web pages played it with a plugin. Then phones and the web moved to MP4, and the plugin is gone.
Where WMV plays, and where MP4 plays
| Where you play it | WMV | MP4 |
|---|---|---|
| Windows 10 and 11 (Media Player, Films & TV) | Yes | Yes |
| Mac (QuickTime, Photos) | No | Yes |
| iPhone and iPad | No | Yes |
| Android phone | Only some apps | Yes |
| Smart TV from a USB stick | Some | Almost all |
| Web browser (Chrome, Edge, Safari, Firefox) | No | Yes |
| iMovie, CapCut and most video editors | Often not | Yes |
| WhatsApp, Instagram, Facebook, YouTube | Upload only, if at all | Yes |
| VLC (any computer) | Yes | Yes |
So if the video should play on an Apple device, go into an editor, or be shared, convert it to MP4.
Why WMV is always re-encoded
A converter could put the WMV picture into an MP4 box without changing it. But almost no player can play Windows Media video inside an MP4. You would get a file with the right name that still does not play.
So this page re-encodes the picture to H.264 and the sound to AAC. Only in the rare case where a WMV or ASF file already holds H.264 video does it repack the picture untouched (in seconds).
| Your choice | What the encoder uses | File size, roughly |
|---|---|---|
| High — larger file | x264 CRF 18 | about 1.5–2× the Good size |
| Good — the usual choice | x264 CRF 23 | the normal size |
| Smaller file | x264 CRF 28 | about ½–⅔ of the Good size |
CRF is a quality number: a lower number means a better picture. In our tests, 5 steps changed the file by 1.5 to 2 times (more on real camera video, less on simple screen video). The sound is always AAC at 192 kbps, which is 1.44 MB per minute. Old WMV files are often small, so Good keeps all the detail they have.
How long does it take?
The encoder runs inside your browser on one processor core. A good rule: about as long as the video itself, sometimes two or three times as long on an older laptop, and slower on a phone. A 5-minute 480p clip from Windows Movie Maker is quick. A 30-minute 1080p recording takes a while — choose 720p to make it faster.
You can switch to another tab while it works. Keep this tab open.
Frequently asked questions
How do I convert WMV to MP4 for free?
Drop the WMV file on the box above, keep Good quality, and press Convert to MP4. When it is done, play the result and press Download MP4. There is no sign-up, no watermark and no upload.
Will I lose quality?
Every re-encode changes the picture a little. At Good you will not see a difference on a normal old WMV. If the video matters a lot (a wedding, a family film), choose High: the file is bigger, but the picture stays closer to the original.
Can I play a WMV on a Mac or an iPhone?
Not with the apps that come with them. QuickTime, Photos and the iPhone do not play Windows Media video. Convert it to MP4 here and it plays on every Apple device.
Why does my WMV not convert?
Some WMV files from old online shops and TV recorders have DRM (copy protection). Nothing outside the licensed player can read them, and this page cannot either. A damaged file can also fail. Try to play it in VLC first: if VLC cannot play it, no converter can.
Is there a file size limit?
There is no upload, so there is no upload limit. The limit is your browser's memory: files up to about 1–2 GB usually work on a computer. Phones handle less.
Is my video uploaded?
No. The converter (ffmpeg) runs inside your browser, on your device. The video never leaves it.
Related tools
- AVI to MP4 — the other old Windows video format
- FLV to MP4 — for old Flash videos and OBS recordings
- Video Converter — convert to MP4, WebM or MKV from many formats
- Compress Video to Size — make the MP4 fit an email or chat limit
- Trim Video — cut the part you want to keep
Credits
Conversion is powered by ffmpeg.wasm (FFmpeg and x264, licensed under GPL-2.0).
How to use it
- Click the box and choose your WMV, or drag it onto the box
- Keep Quality on *Good*, or choose *High* for an important video
- Leave Resolution on *Keep the original*, or choose 720p for a smaller and faster file
- Press Convert to MP4 and wait — the first time also loads the video engine
- Play the result, then press Download MP4
