MKV files often hold H.264 video that just needs a different wrapper to play on phones, TVs and editors. The video is copied as it is, so even a large file converts in seconds.
MKV to MP4 at a glance
| Price | Free, no sign-up, no watermark, no daily limit |
|---|---|
| Accepts | MKV |
| Largest file | 2 GB per file, several files at once |
| Where it runs | In your browser: files are never uploaded |
| Works on | Chrome and Edge, Safari 17+, Firefox 130+ on iPhone, Android, Windows, Mac and Linux |
| Send the result | Download it, or send it free with a link or by email (up to 20 GB) |
How to convert MKV to MP4
- Choose one or more MKV files.
- Keep “Plays everywhere”.
- Press Convert MKV to MP4. The note tells you if only the sound needs converting.
- Download the MP4 files.
Re-packing instead of re-encoding
MKV (Matroska) is a flexible container. When the video inside is H.264, which it usually is, the tool copies it into an MP4 unchanged: same quality, about the same size, done in seconds. HEVC, VP9 and AV1 video are converted to H.264 with “Plays everywhere”, or kept as they are with “Fastest”.
Sound: AC-3, DTS, Opus
MKV files often carry Dolby Digital (AC-3) or Opus sound, which many MP4 players cannot handle. Those tracks are converted to AAC stereo. AC-3 and E-AC-3 are decoded with a built-in decoder that loads only when needed. DTS sound cannot be decoded in a browser; such files are converted without sound, and the result says so.
What is not carried over
The main video and the main audio track are converted. Subtitles, chapters and extra audio languages stay behind, since MP4 players handle them inconsistently. Keep the MKV if you need them.
How this compares
| This tool | Online converters (e.g. Clideo, FreeConvert or CloudConvert) | Desktop apps (e.g. HandBrake) | |
|---|---|---|---|
| Your file is uploaded | No | Yes, to their servers | No |
| Install or account | None | Account for some features | Install needed |
| Watermark or daily limits | None | Common on free plans | Depends on the app |
Plans of other services change; check their sites. More video tools.
Frequently asked questions
Does converting MKV to MP4 lose quality?
No, for H.264 video: it is copied as it is. Only the sound may be converted to AAC, which is transparent at 160 kbps.
Why does my MKV have no sound on my TV?
Often because the sound is AC-3 or DTS. Converting it here gives AAC sound that TVs and phones play.
Are subtitles kept?
No. Only the main video and sound are converted.
Is my file uploaded?
No. It is converted in your browser on your device.
Need to send a big file?
Send files up to 20 GB with a download link or by email. Free, no account needed, original quality.
Send large files free