How to convert FLV to MKV
To convert FLV to MKV, upload your FLV file, choose MKV as the output format and press Convert. The finished MKV file is ready to save to your phone or computer in seconds, free, with no watermark and no sign-up. Your file is deleted from our server about 30 minutes after the conversion.
This free online converter turns FLV videos into MKV files in your browser, with no software to install and no watermark. When the video and audio inside your FLV file can be placed in MKV as they are, the streams are copied without re-encoding, which is faster and keeps the original quality. Otherwise the video is re-encoded as H.264 video with AAC audio.
Reasons to switch from FLV to MKV
- Stores many audio tracks, subtitles and chapters
- Supports almost every codec
- Open and royalty-free
- Plays on: VLC, Plex, Kodi, most Android players and modern Windows; limited on iOS and older TVs
What to expect from this conversion
- Expect a file of similar size to the FLV original.
- Flash is discontinued, and FLV is rarely supported any more, so converting to a modern format keeps the video playable.
- FLV is a legacy format, so moving to MKV makes the video easier to play, edit and share on current devices.
- The first audio track is kept. Subtitle tracks, extra audio tracks and chapters are not included in the converted file.
FLV vs MKV
| Property | FLV | MKV |
|---|---|---|
| Full name | Flash Video | Matroska Video |
| Released | 2002, Macromedia / Adobe | 2002, Matroska.org (open standard) |
| Generation | Legacy | Modern |
| Typical file size | Small | Small |
| Plays on | VLC, MPC-HC, ffplay and legacy RTMP tools; not supported by modern browsers | VLC, Plex, Kodi, most Android players and modern Windows; limited on iOS and older TVs |
| Best for | older streaming servers and RTMP workflows; archival conversions | movie and TV archives with multiple languages; keeping subtitles inside the file |
Steps to convert FLV to MKV
- Drop your FLV video file onto the converter, or click to choose it.
- Check that MKV is selected as the target and adjust the options if you want.
- Press Convert, then download your new MKV file when it finishes.
Tips for the best result
- Leave Fast mode on to keep the original quality whenever the streams can be copied.
- Pick a lower resolution if the file is for a phone or messaging app.
- Use Mute if you only need the picture.
Frequently asked questions
How do I convert FLV to MKV?
Upload your FLV file, make sure MKV is the selected target and press Convert. When the progress bar finishes, download the MKV file. No account or software is needed.
Is the FLV to MKV converter free?
Yes. It is free, with no watermark, no sign-up and no daily limit on how many files you convert. The site is supported by ads.
Will I lose quality when converting FLV to MKV?
Not necessarily. If the video and audio streams already fit inside MKV, they are copied without re-encoding, so quality stays identical. If the file has to be re-encoded, the High setting keeps almost all visible detail, while Small trades some detail for a smaller file.
Will the MKV file be a similar size to my FLV?
Expect a file of similar size to the FLV original. Choosing a lower quality or resolution reduces the size further.
Which devices can play MKV files?
MKV files play on VLC, Plex, Kodi, most Android players and modern Windows; limited on iOS and older TVs.
How large a file can I upload?
You can upload videos up to 500 MB. Files are deleted from the server about 30 minutes after conversion.