MKV to MP4

MKV holds everything but plays in fewer places than it should. Drop an .mkv to convert.

drop a video here

or click to choose

Why convert MKV to MP4?

MKV (Matroska) is a flexible container popular in pirated movies, anime fansubs, and high-quality video archives. It can hold multiple audio tracks, subtitle tracks, and any video codec. But:

iPhone and iPad won't play MKV in the Files or Photos app.
Smart TVs over DLNA often choke on MKV.
Older Android phones and embedded players reject MKV.
QuickTime on Mac needs add-ons.

MP4 (with H.264 video) plays in all those places without setup. This tool re-encodes the video to H.264, keeps one audio track (the first one), and drops subtitles to keep the file size sane.

What about subtitles?

If your MKV has soft subtitles you want to keep, use the burn subtitles tool after this conversion — extract the .srt elsewhere first and then burn it in.

FAQ

What if my MKV has multiple audio tracks?

We keep the first audio track. The others are dropped. For multi-track preservation, use desktop FFmpeg.

Does the file get uploaded anywhere?

No. Open this page, turn off your wifi, then try a file — it still works. That's the test.

What's the maximum file size?

Browser memory is the limit. WebAssembly caps at 2–4 GB per file. Most laptops handle 1080p videos under a gigabyte comfortably.

Why is it slow on my phone?

FFmpeg-WASM runs on your CPU, not hardware video encoders. Phones have less CPU, so encoding takes longer.

Can I cancel mid-encode?

Yes. The Cancel button terminates the worker immediately. You'll wait a few seconds the next time you start.