Convert MKV to MP4
Convert MKV files to MP4 entirely in your browser — no upload, no account, no watermark.
Your file never leaves your device — conversion runs entirely in this browser tab.
To convert MKV to MP4, open the MP4 converter and drop your MKV file in. The conversion runs entirely inside your browser using WebAssembly, so the file is never uploaded. MKV usually holds H.
What to expect from this conversion
MKV usually holds H.264 already, so the video itself often needs no re-encoding. What forces a re-encode is the audio: MKV frequently carries AC-3 or DTS, which MP4 players do not reliably decode. Multiple audio and subtitle tracks will not survive — MP4 keeps only the first of each.
Matroska, an open container that can hold almost any codec plus multiple audio and subtitle tracks. Flexible, but unevenly supported.
Lossy · video
The universal container, normally holding H.264 and AAC. Plays essentially everywhere.
Lossy · video
Both MKV and MP4 discard data to save space, so this conversion compresses something that has already been compressed. Always convert from your original file rather than from an earlier conversion — the losses compound.
How to do it
- Open the MP4 converter
Go to the MP4 converter and drop your MKV file onto it, or click to browse.
- Convert
Press Convert. FFmpeg runs in your browser and shows real progress as it works.
- Download
Download the finished MP4 file. It is created in your browser and never sent anywhere.
Common questions
How do I convert MKV to MP4?
Open the MP4 converter, drop your MKV file onto it and press Convert. Everything runs in your browser — the file is not uploaded. Desktop browsers handle files up to about 200MB; mobile browsers about 40MB.
Does converting MKV to MP4 lose quality?
Yes, some. Both MKV and MP4 are lossy, so this is a second compression pass over data that was already compressed. The loss is usually modest, but always convert from your original rather than from a previous conversion.
Is it free to convert MKV to MP4?
Yes, with no account, no watermark and no daily limit. The processing happens on your device rather than on a server, so there are no per-conversion costs to pass on.
Are my files uploaded when converting MKV to MP4?
No. FFmpeg runs as WebAssembly inside your browser tab. The file is read from your disk, processed in memory and written back out — it never reaches a server.