Treeet
Quick steps
- 01Add MKV filesChoose files or drop them on the page.
- 02Converted on your deviceNothing is uploaded. Adjust settings if you like.
- 03DownloadSave each file, or all of them as one ZIP.
What’s MKV?
A flexible video container, common for films. Many phones and editors won’t play it.
MKV to MP4 converts MKV videos into MP4 files that play on phones, TVs, browsers and video editors. It’s free and runs on your own device with ffmpeg in the browser, so your video is never uploaded.
How to convert MKV to MP4
- Choose a Quality in the settings panel. It only matters if the video has to be re-encoded.
- Choose your MKV file or drop it on the page. The video engine loads on first use, then conversion starts.
- Keep the tab open until it’s done. The progress bar shows how far it has got.
- Press Save or Download to get the MP4.
What happens to your video
MKV and MP4 are containers: boxes that hold video and audio streams. The tool first checks which kind of video is inside.
- H.264 video, the most common kind, is copied into the MP4 unchanged. That’s quick and loses no quality.
- AAC or MP3 audio is copied too. Other audio, such as AC3, DTS, Opus or FLAC, is converted to AAC at 192 kbps so it plays everywhere.
- Any other video, such as H.265/HEVC, VP9 or AV1, is re-encoded to H.264 with AAC audio. That works on almost every device, but it takes much longer.
- The MP4 is saved so it can start playing before it has fully loaded, which helps when you share it online.
What the Quality setting does
When the video is copied, quality stays exactly as it was, whatever this setting says.
- High (bigger file): closest to the original, with larger files.
- Balanced: the default, a good mix of quality and size.
- Small file: noticeably smaller files, with some loss of detail.
Why convert MKV at all?
MKV is a flexible container that can hold almost any video, audio and subtitle format, which is why it’s common for films and screen recordings. That flexibility is also the problem: iPhones, many smart TVs, social apps and editors such as iMovie don’t open MKV files. MP4 with H.264 video and AAC audio is the format nearly everything accepts, so converting is usually the quickest fix when a video won’t play or won’t import.
Limits and common problems
- Only one audio track is kept. If your MKV has several languages, the others are left out.
- Subtitle tracks may not come across. If you need them, keep the MKV as well.
- Re-encoding runs on your computer’s processor inside the browser, which is slower than desktop software. A long HD film can take a long time.
- The whole file has to fit in the browser’s memory. Very large files, several gigabytes, may fail, especially on phones.
- The conversion fails partway: the file may be too big for the browser’s memory. Try on a computer, and close other tabs.
- It’s very slow: the video isn’t H.264 and is being re-encoded. Leave the tab open and let it finish; a computer is much faster than a phone.
- “No audio or video we can read”: the file is damaged or isn’t really a video.
Privacy
The video is processed by ffmpeg compiled to WebAssembly, running in your tab. Home videos and recordings never leave your device.
At a glance
- Price
- Free. No sign-up, no watermark.
- Privacy
- Files are processed in your browser and never uploaded.
- Accepts
- MKV
- You get
- MP4
- Batch
- Convert many files at once and download them as a ZIP
- Works in
- Chrome, Edge, Firefox and Safari, on phones and computers
- Offline
- Keeps working without internet once the page has loaded
Questions
Are my files uploaded?
Never. MKV to MP4 conversion runs in your browser, so your files stay on your device.
Why is it sometimes instant?
If the video is already H.264, we just repackage it without re-encoding.
Can I convert many at once?
Yes. Add as many as you like and download them all as one ZIP.
How long does it take?
Repackaging is quick. Re-encoding runs on your device and is slower for long videos; a computer is fastest.
Does converting MKV to MP4 lose quality?
Not when the video is H.264, because it’s copied unchanged. Other formats are re-encoded, which loses a little detail; choose High to keep the most.
Can I keep multiple audio tracks or subtitles?
No. The MP4 gets one audio track, and subtitles may not be carried over. Keep the MKV if you need them.
Will the MP4 play on an iPhone or a smart TV?
Almost always. The output uses H.264 video and AAC or MP3 audio, which phones, TVs and browsers widely support.
Is there a file size limit?
No fixed limit, but the file must fit in your browser’s memory. Multi-gigabyte files may fail, especially on phones.
Can I convert MP4 back to MKV?
Yes. Use MP4 to MKV, which repackages the video without re-encoding when it can.