MKV to FLV Converter
Convert MKV to FLV free — no upload, no signup
To convert MKV to FLV, drop your MKV video into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. H.264 MKVs become FLV quickly for streaming tools.
Drop videos here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
If the video already uses codecs that fit the new format, Fylo repackages it instantly with no quality loss.
Advanced
How to convert MKV to FLV
Add your MKV videos
Drag and drop MKV files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Choose quality (optional)
Balanced quality suits most videos. If the codecs already fit FLV, Fylo repackages the file instead of re-encoding it, with no quality loss.
Convert and download
Click Convert, then download each FLV file or all of them as one ZIP.
Why convert MKV to FLV?
Restreaming an MKV recording through an RTMP tool that expects FLV is a common reason for this conversion.
What happens when you convert MKV to FLV?
H.264 video is copied, and audio is converted to 44.1 kHz AAC if needed. Other video codecs are re-encoded to H.264.
How does Fylo convert MKV to FLV?
Fylo reads the MKV with ffmpeg compiled to WebAssembly and writes H.264 with AAC audio at 44.1 kHz, the sample rate Flash-era players expect. Most MKV files already contain H.264 video, so Fylo usually copies the video without re-encoding (and converts only the audio if needed), which is fast and lossless. Only the first video and audio track are kept, and the original resolution is preserved unless you pick 1080p, 720p or 480p under Advanced.
What's the difference between MKV and FLV?
MKV is the Matroska container, an open standard first released in 2002. It can hold virtually any video, audio or subtitle codec, and any number of tracks — so one file can carry several languages, director's commentary and subtitles. WebM is a restricted subset of Matroska.
FLV (Flash Video) was introduced with Flash Player 6 and 7 in 2002–2003 and became the format behind early YouTube, news sites and video portals. Later FLVs usually contain H.264 video and AAC audio — the same codecs as MP4.
Learn more: MKV format guide · FLV format guide
| Property | MKV | FLV |
|---|---|---|
| Developed by | Matroska project (open standard) | Macromedia / Adobe |
| Introduced | 2002 | 2003 |
| Typical video codecs | Any: H.264, HEVC, VP9, AV1… | H.264, Sorenson Spark, VP6 |
| Typical audio codecs | Any: AAC, Opus, FLAC, DTS, AC-3… | AAC, MP3 |
| Plays in web browsers | Partly (Chrome/Edge for some codecs) | No (Flash Player ended in 2020) |
| Compatibility | VLC, Plex, Kodi, most smart TVs; not iPhone or many editors | VLC and some desktop players; RTMP live-streaming tools |
| Best for | Movies with multiple audio and subtitle tracks | Old Flash archives, RTMP streaming workflows |
Frequently asked questions
Can I stream the FLV directly?
Yes, tools that accept FLV input can stream it via RTMP.
Will quality drop?
Not for copied H.264 video.
Is my MKV file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your MKV file is read directly from your device and never sent anywhere.
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