Free tool

MKV to MP4 converter for phones, TVs and editors.

Drop an MKV and download an MP4 that plays on iPhone, Android, smart TVs, in browsers and in Premiere or Final Cut.

MKV to MP4 converter at a glance

content.win compresses big files for free, several at once, and never adds a watermark. You can name an exact size in MB and get a file that fits.

Works with
MP4, MOV, WebM and MKV.
Comes back as
MP4, MOV, WebM or MKV, at a quality preset or an exact target size in MB.
Runs
In your browser.
Limits
Up to 10 videos at once, in a browser that can play them. Free space on the device is the only other limit.
Price
Free. No account, no watermark.

How to convert MKV to MP4

  1. Drop the MKV in. One file or several.
  2. Keep the quality, or shrink it. Format is already MP4. "Best quality" keeps it looking the same; a target size makes the file smaller for sharing.
  3. Download the MP4. The main audio track is kept; subtitles inside the MKV are not carried over.

Why MKV needs converting

Phones and TVs
MKV is a flexible container that many phones, smart TVs and streaming boxes do not play, or play without sound. MP4 with H.264 video plays on all of them.
Editors and platforms
Premiere, Final Cut, DaVinci and every upload form accept MP4. MKV is refused or imports with problems.
Multiple tracks
MKV files often carry several audio tracks and subtitle streams. The MP4 keeps the main audio track and the video, which is what players expect.

What happens to the video inside

  • H.264, HEVC, VP9 or AV1 in the MKV, as long as your browser can play it, comes out as H.264 at a high quality, so it plays everywhere.

Questions people ask

Does MKV to MP4 lose quality?

Not visibly with "Best quality": the video is re-encoded at a high, visually identical quality. Choosing a smaller size trades quality for size on purpose.

What about subtitles inside the MKV?

They are not carried into the MP4. Extract them from the MKV with a subtitle tool if you need them.

Which audio track is kept?

The main one: the track marked as the default, or the fullest one when none is. If the MKV has several languages, set the one you want as the default, or remux it before converting.

Why does my TV not play the MKV?

Container and codec support on TVs is limited and inconsistent. An H.264 MP4 is the safe format for all of them.

How big can the file be?

As big as you like; free space on the device is the only limit.

Is there a watermark?

No.