MKV to MP4
Turn MKV to MP4 in seconds, free and with no limit on how many files. Your file is converted on your own device and is never uploaded to our servers.
- Free & unlimited
- No sign-up
- Files never uploaded
- No watermark
- Up to 2 GB per file
How to convert MKV to MP4 in three steps
No install and no account. The converter loads once, then works on any MKV you pick.
- 1
Pick your MKV file
Drop the .mkv on the page or browse for it. Its size, duration and resolution show up before anything runs.
- 2
Keep Fast Copy or choose Re-encode
Fast Copy repackages the streams, and a compatible video stream keeps its exact picture. Re-encode makes H.264 at High, Medium or Small file quality and can scale down to 1080p, 720p or 480p.
- 3
Save the MP4
The file keeps its name, now ending in .mp4. The result screen shows the original and converted size, and, after Fast Copy, says if the video had to be re-encoded and how many audio tracks were converted.
Why this converter keeps MKV quality intact
Most MKV files don't need a new encode at all, just a new wrapper.
A container swap, not a re-encode
MKV and MP4 are both containers. When the video is H.264, HEVC or AV1 in a compatible format, Fast Copy moves the same stream into MP4, so the picture is exactly what you had.
Every audio track comes along
A second language, a commentary, a stereo mix: all audio tracks stay in the MP4, and you switch between them in your player.
Problem audio is fixed on its own
DTS, AC3, Opus and FLAC are common in MKV, but many MP4 players can't decode them. Only those tracks become AAC 192 kbps; AAC and MP3 tracks and the video are still copied.
HEVC tagged for Apple
HEVC video is written with the hvc1 tag, the label QuickTime and Apple devices look for in an MP4.
No upload to wait for
The MKV is read and converted inside this browser tab. A large film is ready as soon as it is read: click Convert and the work starts, with no long upload first.
Ready for the web
The MP4 is saved with its index at the start (faststart), so a browser or video site can begin playing it before the whole file has loaded.
MKV to MP4 converter options compared
The four routes people use, side by side. If your file came from OBS, its own remux tool is a fine choice too.
| This converter | Upload-based online converters | VLC Convert / Save | OBS Remux Recordings | |
|---|---|---|---|---|
| Your video is uploaded | No, it stays on your device | Yes, kept on their servers; retention depends on the service | No | No |
| Install needed | No, runs in the browser | No | Yes, desktop app | Yes, desktop app |
| Default method | Copies streams, converts only what MP4 can't play | Varies by site and settings | Re-encodes with its MP4 profile | Copies streams |
| Waiting time is mostly | Reading the file | Your upload and download | Encoding the video | Reading the file |
| Audio tracks and subtitles | All audio, text subtitles and chapters kept | Depends on the site | Depends on profile settings | Keeps what OBS recorded |
| Best for | Any MKV up to about 2 GB | Users happy to upload | Users who already have VLC | Files recorded in OBS |
| Cost | Free, no sign-up | Limits and pricing depend on the service | Free | Free |
Where an MP4 plays and an MKV doesn't
MKV is common for downloads, rips and recordings. These are the places that turn it away.
iPhone and iPad
Apple's built-in players don't open MKV. After the swap the file plays in Photos and QuickTime, with HEVC tagged the way Apple expects.
PowerPoint and Keynote
Keynote and many PowerPoint versions reject MKV when you insert a video. Insert the MP4 instead; Fast Copy keeps the original resolution.
Premiere Pro and iMovie
Editors that won't import MKV take the MP4 directly, with every audio track still there to choose from.
Smart TVs and game consoles
Many TV, PlayStation and Xbox media players skip MKV, and some play it with no sound when the audio is DTS. The MP4 carries AAC audio instead. If an older TV has no HEVC decoder, choose Re-encode (H.264).
WhatsApp and upload forms
WhatsApp and many site upload forms take MP4 but not MKV. The converted file goes through like any phone video.
OBS recordings
OBS recordings are often MKV, because a recording cut short by a crash usually stays playable. Convert the finished recording here, or use Remux Recordings if OBS is already open.
Anime and movie rips with subtitles
SRT and ASS subtitles come through as soft subtitles you turn on and off. Blu-ray image subtitles don't; the next section explains why.
Audio tracks, subtitles and chapters after converting MKV to MP4
Every audio track in the MKV is kept, in its original order. Each track is handled on its own: AAC and MP3 tracks are copied as they are, while AC3, E-AC3, DTS, Opus, Vorbis, FLAC, MP2 and AMR tracks are converted to AAC at 192 kbps, because MP4 players often can't decode them. After Fast Copy, the result screen says how many audio tracks were converted. With Re-encode, every track becomes AAC.
Text subtitles (SRT, ASS/SSA and WebVTT) become MP4 soft subtitles that you switch on in the player. ASS styling such as fonts, colors and positions is lost; the words and timing stay.
Image subtitles, PGS from Blu-ray and VobSub from DVD, are pictures rather than text, and MP4 can't hold them, so they are dropped. If you watch with them, keep the original MKV. Chapters are kept. Attached fonts are dropped, since MP4 has nowhere to put them.
Common MKV to MP4 mistakes
Mistake: Re-encoding a film that only needs a new container.
Do this instead: Leave Fast Copy on. A 543 MB 1080p H.264 MKV took about 2.5 seconds in our test, while re-encoding 1080p runs at about real time.
Mistake: Renaming the file from .mkv to .mp4.
Do this instead: That changes the name, not the container, so many players still refuse it. Convert it so the streams are written into a real MP4 structure.
Mistake: Expecting Blu-ray subtitles to survive.
Do this instead: PGS and VobSub are images, and MP4 drops them. Keep the MKV for watching with those subtitles.
Mistake: Loading a file much bigger than 2 GB.
Do this instead: The browser runs out of memory around that size. Use a desktop tool such as FFmpeg or OBS Remux for those files.
Privacy, cost and limits
Your video stays with you
Conversion happens in the tab. The site only sends you the converter program; your file never travels to our servers, so there is nothing for us to store or delete.
Free, with unlimited conversions
No sign-up, no watermark and no limit on how many videos you convert. Files go one at a time; there is no batch queue.
About 2 GB per file
WebAssembly in the browser has a memory ceiling. We converted a 1.6 GB MKV without trouble; a 2.1 GB file stopped with an out-of-memory message.
A 32 MB first load
The first visit downloads the converter, FFmpeg 5.1.4 built for WebAssembly, from jsDelivr. Later visits load it from your browser cache.