MKV to MP4 Converter

Runs in your browser — your files are never uploaded.

Turn a Matroska (.mkv) file into a widely-compatible MP4. MKV is a flexible container that can hold almost any codec, so OkConverter tries a fast remux first and automatically falls back to a full re-encode when the source codecs aren’t MP4-compatible — all running locally via ffmpeg compiled to WebAssembly.

OptionsResolution: Original

How to convert MKV to MP4

  1. 1

    Drop your MKV file onto the box, or click to choose one.

  2. 2

    OkConverter tries a fast remux first, re-encoding automatically only if needed.

  3. 3

    Click “Download” to save the MP4.

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Frequently asked questions

Why do some MKV files convert instantly and others take longer?+

MKV can hold many different codecs. If yours is already H.264/AAC, a fast remux (no re-encode) succeeds instantly. Codecs MP4 can’t hold directly (like VP9 or many subtitle/audio tracks) trigger an automatic re-encode instead.

What happens to subtitle tracks?+

This tool converts video and audio only — embedded subtitle tracks are not carried over to the output MP4.

Is my video uploaded anywhere?+

No. Conversion runs entirely in your browser using WebAssembly ffmpeg — nothing is uploaded.

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