Convert any video file to MKV format online for free. Fast, secure, and easy-to-use video to MKV converter with no software installation required.
or click below to browse
Max file size: 50 MBMax duration: 30 min
Sign up for increased limitsA free account gets you up to 50 MB and 30 min.
Drag and drop your FLV file, or click to browse for it.
Choose MKV as the output and click Convert. The conversion runs on our servers, so your device does none of the work.
Download your converted file instantly. The download link expires in 1 hour for security.
Our powerful servers process your files quickly, delivering converted files in seconds.
Convert your files completely free with no hidden costs or subscription fees.
Your file is used only to make your conversion. It is never published or shared, and the download link expires after one hour.
Works directly in your web browser. No software download or installation required.
How the two formats differ on the things that change your result.
| Specification | FLV (source) | MKV (result) |
|---|---|---|
| Container | Flash Video | Matroska |
| Developed by | Adobe (Macromedia) | Matroska.org |
| Introduced | 2002 | 2002 |
| Video codecs | H.264, Sorenson Spark, VP6 | H.264, H.265, VP9, AV1 |
| Audio codecs | AAC, MP3 | AAC, FLAC, Opus, AC-3, DTS |
| Max resolution | Full HD (1080p) | 8K UHD |
| Typical bitrate (1080p) | 1–8 Mbps | 8–40 Mbps |
| Multiple audio tracks | No | Yes |
| Subtitle tracks | Not supported | Embedded (soft) subtitles |
| Chapter markers | No | Yes |
| Streaming optimized | Yes | No |
| Licensing | Proprietary | Royalty-free |
| Plays natively on | Needs a player: Windows, macOS | Native: Windows · Needs a player: macOS, iOS, Android, Smart TVs |
| Best for | legacy archives, web archives | media archives, multi-language releases, home theatre |
Because MKV supports H.264 just like FLV does, the video stream can be carried across without a quality-costing re-encode.
At 1080p, FLV typically runs around 4.5 Mbps while MKV sits near 24 Mbps, which is the main driver of the size difference you will see.
This is an older container, introduced in 2002, and browsers will not play it directly. It is best suited to archival or a dedicated player.
This page converts FLV video, stored in the Flash Video container since 2002, into MKV, which uses Matroska and dates from 2002. The codecs each container accepts decide whether the picture has to be re-encoded.
FLV comes from Adobe (Macromedia) and dates to 2002. It usually holds H.264, Sorenson Spark, or VP6 video with AAC or MP3 sound, and those streams set the ceiling for anything converted out of it.
MKV comes from Matroska.org and dates to 2002. It holds H.264, H.265, VP9, or AV1 video alongside AAC, FLAC, Opus, AC-3, or DTS audio, and without installing anything it plays on Windows.
After converting your file, you can use Scriptivox transcription services to convert your audio to text. Perfect for meetings, interviews, podcasts, and more.
Quick access to the most commonly used file conversions
And many more format conversions supported