ASF to MKV converter
Convert ASF to MKV in seconds, free and unlimited. No upload, no sign-up, no watermark: your video never leaves your device.
Last updated
Quick answer: To convert ASF to MKV, add the ASF file to the iHateFiles ASF to MKV converter and press Convert. The conversion runs in your browser, so the file is never uploaded, and it is free with no sign-up, watermark or size limit. ASF is a format most software has stopped opening. MKV is not.
Should you convert ASF to MKV?
Yes. ASF is a format most current software no longer opens, so converting it is the reliable way to keep watching it. MKV is a reasonable target; MP4 is the safest.
The picture is re-encoded
An ASF usually holds Windows Media video and audio. This writes H.264 video with AAC sound into the MKV. Both sides are compressed with loss, so this is a second generation: leave the quality at its default or higher, because the encoder is working from ASF artefacts rather than the original.
Expect a smaller MKV
H.264 video is a much more efficient codec than what an ASF holds, so at the same visual quality the MKV is usually a third to a half of the size.
Where the MKV will play
MKV plays on VLC, Plex, most smart TVs and Android, but not the iPhone Photos app or QuickTime.
ASF and MKV side by side
| ASF | MKV | |
|---|---|---|
| Inside the file | Windows Media video and audio | H.264 video with AAC sound |
| Compression | Lossy | Lossy |
| Carries sound | Yes | Yes |
| Plays on | Needs converting first | VLC, Plex, most smart TVs and Android, but not the iPhone Photos app or QuickTime |
| Here | Read only | Read and write |
What usually goes wrong
About the ASF. ASF, WMV and WMA all share the same file signature, so identifying which one you have means looking at the streams inside rather than the first few bytes.
About the MKV. MKV and WEBM share a signature because WEBM is a restricted Matroska, so tools sometimes report one as the other. What matters is the codecs inside.
How to convert ASF to MKV
- Add your ASF file. It is read from your disk and stays there.
- Check the settings. The output format is already set to MKV.
- Press convert and the MKV file is saved back to your device.
Questions
How do I convert ASF to MKV?
Open this page, add your ASF file, and press convert. The file is decoded and re-encoded by your own browser and saved back to your device. Nothing is uploaded.
Is this ASF to MKV converter free?
Yes, completely. There is no account, no sign-in, no watermark and no daily limit, because there is no server doing the work. Your own device does it.
Are my files uploaded anywhere?
No. There is no upload endpoint. The conversion runs inside this browser tab, so your file never leaves your device. You can open your browser's network panel and watch: nothing carrying your file is sent.
Is there a file size limit?
No fixed limit. Because the work happens on your machine there is no server quota. The only ceiling is your own device's memory, which for video means very large files may be slow.
Will converting to MKV lose quality?
MKV is a lossy format, so some detail is discarded. The quality control on this page decides how much. The default is set high enough that most people cannot see the difference.
Can I convert several ASF files at once?
Yes. Add as many as you like and they are converted one after another, then offered as a single ZIP.