Convert to and from MKV, free.
MKV (Matroska) is an open container that can hold any codec plus unlimited audio tracks, subtitle tracks and chapters. That flexibility makes it great for archives and useless for sharing.
Convert something else to MKV
Pick what you have. Each page opens the editor with MKV already selected as the output.
Convert MKV to something else
Pick where it is going. Browsers, phones and social uploads reject MKV almost universally.
MKV next to the formats it converts with
Where each one plays, what it is for and how heavy it is, so you can pick the target before you open a converter.
MKV
MP4
WebM
MOV
AVI
TS
GIF
MP3
WAV
WMV
FLV
VOB
| Format | Best for | Plays on | File size |
|---|---|---|---|
| MKV | Archiving with multiple audio and subtitle tracks | VLC and desktop players; rarely anywhere else | Depends entirely on the codec inside |
| MP4 | Sharing anywhere, uploads, web embeds | Every phone, browser, TV and editor | Small for the quality |
| WebM | Web embeds and browser recordings | Chrome, Firefox and Edge; hit and miss elsewhere | Very small at the same quality |
| MOV | Editing on a Mac, footage straight off an iPhone | macOS and iOS natively, patchy elsewhere | Large, especially ProRes |
| AVI | Opening archive footage from the 2000s | Desktop players with the right codec pack | Very large for the quality |
| TS | Broadcast capture, camcorder cards, HLS segments | Desktop players and streaming servers | Larger than MP4 for the same footage |
| GIF | Short silent loops in docs, chat and email | Everywhere an image can be shown | Huge for anything over a few seconds |
| MP3 | Podcasts, voice notes, music you need to send | Every device made in the last 25 years | Roughly a tenth of uncompressed audio |
| WAV | Editing, mastering, voiceover work | Every desktop and audio tool; large for phones | About 10 MB per minute in stereo |
| WMV | Legacy Windows workflows and old PowerPoint decks | Windows; almost nothing else | Moderate, but dated compression |
| FLV | Nothing new: Flash reached end of life in 2020 | Desktop players only, with effort | Moderate, heavily dated |
| VOB | Ripping the contents of a DVD you own | DVD players and VLC | About 1 GB per chunk, several per disc |
What MKV actually is
Matroska
Almost anything: H.264, HEVC, AV1, VP9
Archiving with multiple audio and subtitle tracks
VLC and desktop players; rarely anywhere else
Depends entirely on the codec inside
Keeps multiple audio and subtitle tracks in one file.
Browsers, phones and social uploads reject MKV almost universally.
Editing tools often refuse to import it, or import picture without audio.
Nobody can preview it without installing VLC first.
An MKV often holds several audio languages and subtitle tracks. Converting renders one video and one audio track, so extra languages and embedded subtitles are not carried over; add captions in the editor instead.
Browsers, iPhones and most upload forms do not accept MKV, which is why a file that plays in VLC still needs converting before it can be shared.
Questions about MKV
What is an MKV file?
MKV (Matroska) is an open container that can hold any codec plus unlimited audio tracks, subtitle tracks and chapters. That flexibility makes it great for archives and useless for sharing. It is the Matroska container, usually holding Almost anything: H.264, HEVC, AV1, VP9.
Is converting MKV free?
Yes. Convert and preview free, and a free account downloads the result. Free exports and share pages include a small REQO badge. Go Pro to remove it. Nothing is installed.
Will converting to MKV lose quality?
Some, whenever the codec changes: every re-encode discards detail. Where the container can simply be rewritten around the existing streams it is lossless, and where it cannot the default settings are chosen so the loss is not visible at normal viewing size.
Other formats
Convert it, then keep editing.
Every converter opens the full editor, so you can trim, caption and share without uploading the file twice.