MKV files are popular with people who download or archive video, but they are awkward in everyday life. Your TV skips them, a phone gallery ignores them and many upload forms refuse them. Turning an MKV into an MP4 solves nearly all of that.
On this page you can convert MKV to MP4 in your browser, with no upload and no account. The good news is that many MKV files only need repackaging, so the job is often much faster than you would expect. Here is how it works, what you might lose and how to deal with files that behave differently.
How to convert an MKV file to MP4
- Drop your .mkv file onto the tool above.
- Confirm that "Convert to" shows MP4.
- Leave Quality on Balanced. For many MKV files it makes no difference, as explained below.
- Press Convert.
- Save your MP4, or download several results at once as a zip.
The conversion runs on your own computer. Your video is not sent to a server, which matters for large personal archives and work recordings. This free MKV to MP4 converter adds no watermark, and video tools are not counted in the free daily limit.
What an MKV file is and why people use it
MKV stands for Matroska, an open container format. A container is the box that holds the parts of a video: the picture, one or more sound tracks and often subtitles. Matroska is flexible, so it can hold many tracks at once, such as several languages, and it can wrap a wide range of picture formats.
That flexibility is also the reason it is not accepted everywhere. A device that understands MP4 may not understand Matroska, even when the picture inside would play fine. This is the usual cause when an MKV will not play on a TV, a console or a phone.
| MKV | MP4 | |
|---|---|---|
| Strength | Holds many tracks in one file | Plays on almost any device |
| Common use | Archives, downloads, disc rips | Sharing, uploads, phones, TVs |
| Picture inside | Almost any video format | H.264 when made with this tool |
MKV to MP4 without losing quality: remux or re-encode
Whether the quality is kept depends on the picture inside the MKV. If it is H.264, the format almost every device plays, the tool copies it into the MP4 without re-encoding. Moving the same picture into a new container like this is called a remux. When the tool can remux MKV to MP4, the result is lossless and the wait is short, and the Quality control tells you "This video is copied as it is into the new format, so the quality does not change it."
If the picture is in another format, such as HEVC (H.265), VP9 or AV1, the tool re-encodes it to H.264 so the MP4 plays widely. In that case Quality decides the result. Balanced stays visually close to the original, Smaller makes a lighter file and Best keeps the most detail. Each one shows an estimated size. The sound is copied too when it is already AAC; any other sound is re-encoded once to AAC.
What happens to extra tracks?
MKV's strength is holding many tracks, but the MP4 you get is kept simple: one picture and one sound track. Any other sound tracks, such as extra languages, and all subtitle tracks are left out. If you rely on them, keep your MKV file as well and treat the MP4 as the version for sharing. Only need the sound? Save it as an MP3, which takes an MKV too.
Need subtitles in the picture?
Subtitles that sit as a separate track will not show on devices that ignore them. If you want text on screen for everyone, use add subtitles to video to write them into the picture.
Convert MKV to MP4 on Windows or Mac
There is nothing to install. On a Windows PC or a Mac, open this page in current Chrome, Edge or Firefox and the converter runs right there, with the same steps on both.
When your browser can read an MKV file, it is handled the fast way and there is no size limit. If your browser cannot, the conversion is slower and accepts files up to 2 GB. The note beside the button tells you which applies: "Fast, on this device. Nothing uploaded" or "Slower for this file, on this device".
- In an older browser, the conversion runs the slower way instead.
- A very large file mostly costs time, not quality, when it is only repackaged.
- Keep the tab open until the Convert button finishes.
- Switch off "Keep the sound" only when you want a silent MP4.
If the MP4 is still bigger than you need, run it through compress video. If it is too long, trim video cuts it first. You can read more on how files are handled on the privacy page.
Where MKV files come from, and why MP4 helps
MKV files tend to arrive from a few places. Some screen recorders can save straight to Matroska. Video you have saved from the web or ripped from your own discs often comes as MKV too. Either way, you end up with a file that plays on your computer but not on much else.
MP4 is the opposite: slightly less flexible, but accepted almost everywhere. That trade is exactly what you want when the goal is to share, upload or play a video on a device you do not control.
- Game and screen recordings you want to post or send to a friend.
- A video for a presentation tool that only lists MP4.
- Footage you want to put on a TV via a USB stick or a streaming box.
- A clip for an editing app that does not open Matroska.
A simple way to check the result
After saving, open the MP4 in the player you plan to use, skim to the middle and the end, and listen for the sound. If you rely on a feature that Matroska held but the MP4 does not, such as a second language, you will notice straight away, and your original MKV is still untouched.
Converting a batch is just as easy. Drop all your MKV files in together, press Convert once and take the zip. Because each file is handled on your own computer, a big batch is limited only by your patience and your disk space, not by a server queue. The tool shows the estimated size of the MP4 under each Quality option, so you can judge the space you need before you start.
Make your MKV play everywhere
To convert MKV to MP4, drop the file into the tool above and press Convert. When the picture is H.264 that is a quick repackage with no loss of quality, and nothing leaves your computer. Your original MKV is never changed, so you can keep it as the master copy. Convert one file first and check it plays where you need it, then do the rest of the batch with the same settings. That small habit saves time and keeps your archive safe, and the same steps work each time you convert MKV to MP4.
Need another format? The convert video page covers MP4, WebM, MOV and MKV.
