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MKV to MP4 Converter — Free, No Upload, No Watermark

Convert MKV to MP4 online: make MKV files play on phones, TVs and editors, often without re-encoding. Free, no upload, runs in your browser.

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Drop a file here or click to browseMKV files — converted on your device, never uploaded🔒 Processed on your device — never uploaded

A video that can be copied across without re-encoding keeps its original quality, whatever you choose here.

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Convert MKV to MP4 without uploading your video

MKV is a fine container for keeping video, but phones, many TVs, web browsers and common editors will not open it. Converting to MP4 makes the same video playable almost everywhere. If the video inside is H.264, the picture is copied across unchanged, so the conversion takes seconds.

Why MKV files will not play

Matroska can hold any video codec, several audio tracks and subtitle tracks, which is why it is popular for downloads and rips, but device makers do not all support it. Phones and TVs often play MP4 and not MKV, and browsers will not play an MKV file in a web page.

What is kept and what is dropped

The converter keeps the first video stream and the first audio stream. Extra audio languages, subtitle tracks and chapters are not carried across, because a standard MP4 handles them poorly. If you need subtitles on screen, add them to the finished video with add subtitles to video.

Large files

MKV files are often several gigabytes, and a browser cannot open a file over about 2 GB. For those, cut a smaller piece first with the video trimmer, or use a desktop tool such as HandBrake or FFmpeg itself.

How this converter works

The page reads your MKV file's header first. If the picture is H.264 and the sound is AAC or MP3, they are copied into the new MP4 without re-encoding, which takes seconds and loses nothing. Anything else is re-encoded to H.264 and AAC at the quality you choose, so the result plays everywhere.

Frequently asked questions

How do I convert MKV to MP4?
Drop your MKV file into the box above, or click to choose it, pick a quality and press Convert to MP4. When it finishes, press Download. The conversion runs in your browser, so the video stays on your device.
Is my video uploaded when I convert it?
No. The conversion runs inside your browser with a WebAssembly build of FFmpeg, and only the engine itself, about 31 MB, is downloaded, once. Your MKV file never leaves your device, and there is no watermark and no account.
Will converting MKV to MP4 reduce the quality?
Often not. If the picture inside the MKV is already H.264 with AAC or MP3 sound, it is copied into the MP4 unchanged. Otherwise it is re-encoded once, to H.264 and AAC, at the quality you choose, and the difference is hard to see at Balanced or High.
What is a MKV file?
MKV is the Matroska container, an open format that can hold any mix of video, several audio tracks and subtitles in one file. It is common for downloaded and ripped video, and it plays in VLC and many media players but not on most phones, TVs or browsers by default.
What is MP4?
MP4 is the most widely supported video container. It usually holds H.264 (sometimes HEVC) video with AAC sound, and it plays on practically every phone, computer, TV and browser, which makes it the safe default for sharing and uploading.
Why does my MP4 have the wrong audio after converting from MKV?
The converter takes the first audio track in the file. Many MKVs list the original language first, but some put a commentary or another language first. This converter cannot choose a different track, so for those files use a desktop tool.
Can I keep the subtitles when converting MKV to MP4?
Subtitle tracks are not carried across. If you have the subtitles as an SRT file, the add subtitles to video tool can burn them into the finished MP4 or add them as a selectable track.

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