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Convert MKV to MP4

Turn your MKV files into MP4 — free, fast and right in your browser.

Runs locally — nothing is uploaded

Drop MKV files here — or click to browse

Files are converted in your browser and never uploaded.

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This tool converts MKV files to MP4 right in your browser. Drop the file, wait a moment for the assessment, convert — the video is processed on your device and never uploaded anywhere. Wherever possible the picture data is repackaged unchanged, which takes seconds and costs no quality.

What is MKV?

MKV (Matroska) is the open container that can hold practically anything: several video and audio tracks, subtitles, chapters and cover art in one file. The IETF published it as RFC 9559 in 2024. Recording software (OBS records to MKV because a crash cannot ruin the file), video rips and downloads use it a lot. What it is not is universally playable — smart TVs, phones and most editing suites expect MP4. Since MKV and MP4 frequently hold the very same H.264 or HEVC stream, the switch is usually just a change of packaging.

What is MP4?

MP4 (ISO/IEC 14496-14) is the everyday video container: H.264 or HEVC pictures plus an AAC audio track, produced by every phone camera, screen recorder and streaming platform. Container and codec are two different things — an .mp4 file says how the data is packaged, not how it was compressed. That distinction is what makes fast conversion possible: if the pictures inside are already H.264 or HEVC, they can simply be repackaged instead of re-encoded. A typical consumer clip carries its sound at 128 to 192 kbit/s AAC.

Why convert MKV to MP4?

MKV is the container for recordings and collections: OBS records to MKV because a crash cannot ruin the file, and rips land there complete with several audio tracks and subtitles. Playing that back needs a well-equipped player though — TVs, tablets, phones and editing suites expect MP4.

Is quality preserved when converting MKV?

In the vast majority of cases yes, because MKV (published by the IETF as RFC 9559 in 2024) and MP4 often hold exactly the same H.264 or HEVC stream — they just wrap it differently. The packets are then copied unchanged: no quality loss, no recalculation, a two-hour film is repackaged in under a minute. Only if the MKV holds VP9, AV1 or an exotic codec does it have to be re-encoded.

What are the limits?

Whatever MKV can do and MP4 cannot is lost: one video and one audio track are carried over. Additional language versions, embedded subtitles, chapter marks and attached fonts stay behind. If the audio is DTS or AC-3 from a film rip, it is re-encoded to AAC so the MP4 has sound everywhere. For an archive with all tracks, the MKV remains the better file — keep it if you need both.

How to convert

1. Drop your MKV file(s) into the area or click to browse. 2. The tool reads the header and tells you whether it will repackage or re-encode, and roughly how long that takes. 3. Click Convert — progress is shown per file and you can cancel at any time. 4. Download the MP4; multiple files come as a ZIP.

Frequently asked questions

Is converting MKV to MP4 free?

Yes, completely free and without signup. There are no watermarks and no file-size limits beyond what your browser can handle.

Are my files uploaded?

No. The conversion runs entirely in your browser — your MKV file never leaves your device and is not sent to any server.

Do I lose quality converting MKV to MP4?

Usually not. If the MKV already holds H.264 or HEVC with AAC or MP3 sound, the picture data is copied into the MP4 container unchanged — bit for bit the same image, just packaged differently, and done in seconds. Only when the codecs do not fit MP4 (VP9 or AV1, for example) is it re-encoded, which costs a little quality once. The tool shows you which path applies to your file before you start.

Can I convert several files at once?

Yes. Just drop multiple files into the area — they are converted together and you can download them as a ZIP.

How big and how long may the video be?

Up to 2 GB in size. When the file is only repackaged, up to two hours of runtime works — that is fast and needs little memory. When it has to be re-encoded, the limit is 30 minutes, because every frame goes through the encoder individually and the tab has to stay open. Which case applies to your file is shown before you start.

What happens to extra audio and subtitle tracks?

One video and one audio track are carried over — that is what an MP4 transports reliably everywhere. Additional language versions, embedded subtitles and chapter marks stay behind. If you need them, keep the original file as well.

Why does it take seconds for some files and minutes for others?

Because there are two paths. If the codecs fit into an MP4 container, the finished data packets are merely rearranged — pure copying, done in seconds. If they do not, every frame has to be decoded and encoded again, and then the wait is roughly in the order of the video length. The work is done by your device’s encoder, not by a server.