Converting MP4 to MKV
This page is the MP4 to MKV setting of our converter, with MKV already chosen. Drop a MP4 file in and the result comes back as MKV — no account, no queue, and no watermark on the output.
The conversion runs entirely inside your browser tab. Your file is read into memory on your own machine, converted there, and handed straight back. Nothing is uploaded, which means there is no size limit imposed by someone else's bandwidth and no copy of your file sitting on a server after you close the tab.
What is MP4?
H.264 in an MP4 container. Plays on effectively every device made this century, and the right default for sharing.
What is MKV?
A flexible container that can hold almost any stream. Popular for archived media, accepted by very few web players.
What changes in this conversion
This is a full re-encode: every frame is decoded and compressed again. In the browser that runs far slower than native software, so expect minutes rather than seconds on a long clip.
Is it really free?
Yes, and there is no catch to explain. Because the work happens on your device rather than on a server, running this costs us nothing per conversion — so there is no bill to recover and nothing to gate behind a sign-up, a daily quota or a watermark.