MKV to MP4 Converter
Turn MKV recordings and clips into MP4 that plays on iPhone, Mac, in browsers and in social apps. Free, with no account and no watermark.
Output: MP4 with H.264 video and AAC audio, the most widely supported combination.
Need more changes? Continue in the full editor after downloading or processing the converted file.
How to convert MKV to MP4
The converter re-encodes the video into a standard MP4 file. You do not need to choose a codec, quality or resolution.
Step-by-step
- Choose an MKV file or drag it onto the upload area.
- Wait for the upload to finish, then click Convert to MP4.
- Wait while the video is converted. Long or 4K videos take longer.
- Download the MP4 and play, edit or upload it where the MKV did not work.
What you get
The result is built for compatibility rather than for the smallest possible size:
- H.264 video with 8-bit 4:2:0 color, which practically every phone, computer, TV and browser can play.
- AAC audio, the standard audio format for MP4. AC3, DTS, Opus, FLAC and other audio formats common in MKV are converted to it.
- One audio track: the one marked as default in the MKV. Other audio tracks and embedded subtitles are not included.
- HDR and 10-bit video converted to standard 8-bit video, so colors do not look washed out on regular screens.
- The original resolution and frame rate. An odd width or height is rounded down by one pixel, because H.264 needs even dimensions.
- Fast start for the web: the MP4 can start playing in a browser before it has fully downloaded.
Why an MKV file may not open
MKV (Matroska) is an open container that can hold almost any video and audio codec, several audio tracks, subtitles and chapters. That flexibility is the problem: many devices and programs do not support the container at all. The iPhone Photos app, QuickTime Player, iMovie and Final Cut Pro do not open MKV, and many websites and upload forms do not accept it.
Even a player that opens MKV can fail on the codecs inside. 10-bit HEVC video may play with stutter or not at all on older hardware, and AC3 or DTS audio, common in films, is not supported by many browsers and phones, so the video plays without sound. MP4 with H.264 and AAC avoids both problems.
MKV and MP4: what is the difference?
Both are containers: they store video, audio and other tracks, but they are not codecs themselves. MKV supports more codecs and features, such as many audio and subtitle tracks with styled subtitles. MP4 supports fewer but plays almost everywhere, which is why it is the safer choice for sharing.
If the MKV already contains H.264 video and AAC audio, it can be remuxed: moved into an MP4 container without re-encoding, with no quality loss. This converter always re-encodes, so it also fixes files whose codecs MP4 players cannot handle. It takes longer than a remux, and the result is not a bit-for-bit copy.
MKV recordings from OBS Studio
Many OBS Studio setups record to MKV for a good reason: if OBS or the computer crashes, the MKV stays playable up to that point, while an interrupted regular MP4 recording is usually unreadable. The downside is that the recording then has to be converted before you can edit or upload it.
If you still have OBS, File > Remux Recordings turns MKV into MP4 in seconds without re-encoding, and OBS can also do this automatically after every recording (the remux option in Settings > Advanced). Use this converter when you do not have OBS at hand, when the remuxed file still does not play, or when you need an MP4 with H.264 and AAC.
When to convert MKV to MP4
Convert when the MKV has to work somewhere that expects MP4:
- Playing on an iPhone, iPad or Mac, or on a TV or player that does not open the file or plays it without sound.
- Uploading to a social app, website, LMS or online form that accepts only MP4.
- Editing in iMovie, Final Cut Pro or other software that does not import MKV.
- Sending a screen recording or game clip to someone who has no player for MKV.
Quality, file size and limits
The MP4 can be larger or smaller than the MKV, depending on the original codec. If the result is too large to share, run it through the video compressor.
Files can be up to 200 MB, which suits screen recordings, game clips and short videos, but not a full-length film. Embedded subtitles are not kept. If you have them as a separate SRT file (MKVToolNix can extract one from an MKV), add them to the MP4 with the subtitle tool. For longer videos, use the full Deus Video online editor: it accepts files up to 1 GB, with no size limit on the Maxi plan, and exports MP4.
Trim, subtitle or convert the MP4
WebM to MP4 Converter
Turn a WebM recording or web video into an MP4 that plays almost everywhere.
Trim Video
Keep only the part you need, for example to fit a long recording into 200 MB.
Add subtitles (captions)
Add subtitles from an SRT file to the MP4, since embedded MKV subtitles are not kept.
Convert Video Format
Choose WebM, MOV, AVI or another output format instead of MP4.
Need to Edit Your Video?
Continue with trimming, resizing, cropping, text, subtitles, audio, and other edits in the full editor.
Learn more about MKV and MP4
Frequently Asked Questions
Common questions about converting MKV files to MP4.
Is the MKV to MP4 converter free?
Yes. It is free, you do not need an account, and the MP4 has no watermark.
Will converting MKV to MP4 reduce quality?
The video is re-encoded, so it is not lossless, but the settings keep the original resolution and frame rate and aim to keep the difference hard to see. HDR video is converted to standard dynamic range so it looks right on ordinary screens.
Are subtitles from the MKV kept?
No, embedded subtitles are not included in the MP4. If you have the subtitles as an SRT file, you can add them to the converted video with the subtitle tool.
My MKV has several audio tracks. Which one is kept?
The MP4 gets one audio track: the one marked as default in the MKV, usually the first. Other languages and commentary tracks are not included.
Should I use OBS remux or this converter?
If you have OBS, try File > Remux Recordings first: it is faster and keeps the quality exactly. Use the converter when you do not have OBS, when the remuxed MP4 does not play, or for MKV files from other sources.
Is there a file size limit?
Yes, files can be up to 200 MB. If a recording is larger, trim it first and convert only the part you need.