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MKV to MP4 Converter
Convert MKV to MP4 video — free and unlimited. No sign-up, no watermarks, no monthly limits. Full quality preserved. Files deleted after 1 hour. Powered by FFmpeg.
Upload your MKV file
Drag & drop or click to browse · Max 500 MB
How to convert MKV to MP4
Upload your video
Drag & drop your video file. Up to 500 MB supported.
Set output quality (optional)
Adjust bitrate, quality preset, or use the smart defaults.
Download your file
Hit Convert and download when ready. Conversion is server-side and fast.
About converting MKV to MP4
MKV and MP4 are both containers, and the reason to convert between them is almost never quality — it is compatibility. Matroska will hold practically any codec, which is why it is the format of choice for archiving, and exactly why an iPhone, a smart TV or a browser will often refuse to play it.
The conversion re-encodes video to H.264 and audio to AAC, the pair that plays everywhere without a codec pack: every browser, every phone, every set-top box. The video is scaled to even dimensions and written as yuv420p, because odd dimensions and exotic pixel formats are the two things that make a technically valid file fail on a TV.
Quality is controlled by CRF, a constant-quality target rather than a fixed bitrate: the encoder spends whatever bits each scene needs to hold that quality. The default of 23 is visually transparent for most material.
What actually changes
- Video
- H.264 at your chosen CRF — constant quality, so complex scenes get more bits instead of being starved by a fixed bitrate.
- Audio
- AAC at 192 kbps, which every player supports natively.
- Compatibility
- Even dimensions and yuv420p, the two requirements that most often make an otherwise valid file refuse to play on a TV or a phone.
- Preset
- The speed/size trade-off is adjustable; slower presets give a smaller file at the same quality.
What it cannot do
Every conversion loses something. These are the limits of this one, stated up front rather than discovered in the output.
- Subtitle tracks and chapters are not carried across — MKV holds far more of both than MP4 can.
- Only the first audio track survives; MKV files with several language tracks lose the rest.
- This is a re-encode, not a remux, so there is a generation of loss. A lower CRF reduces it.
- Files up to 500 MB.
Frequently Asked Questions
Why will my MKV not play but the MP4 will?
Because MKV can hold codecs your device has no decoder for. Converting to H.264 video and AAC audio in an MP4 container gives you the combination that plays natively on essentially every browser, phone and TV.
Do subtitles come across?
No. MKV supports subtitle formats and multiple tracks that MP4 cannot represent, so they are dropped. Extract them separately if you need them.
What does CRF do?
It sets a constant quality target rather than a fixed bitrate, so each scene gets the bits it needs. Lower is better quality and a bigger file; 23 is visually transparent for most material.
Is quality lost?
Some — this is a re-encode rather than a container swap. At the default CRF the difference is not visible in normal viewing.