How to convert MKV to MP4
- 1
Drop your MKV file into the converter above, or click to browse. Nothing is uploaded — the file stays on your device.
- 2
Adjust the settings (quality, resolution, and trim). Tip: OBS recordings are usually high-bitrate — quality 70–80 typically halves the size with no visible difference.
- 3
Click “Convert to MP4”. The conversion runs locally in your browser — larger files take longer, and a progress bar keeps you posted.
- 4
Preview the result and hit Download to save your MP4 file.
Why convert MKV to MP4?
Matroska (MKV) can hold any codec plus multiple audio and subtitle tracks, which makes it flexible for recording but unreliable for playback: browsers can't play it, phones choke on it, and editors often refuse to import it.
Converting to MP4 re-encodes the video to H.264 and audio to AAC — the combination every device understands. If you record with OBS, this is the step that turns your crash-safe MKV recordings into files you can actually share and edit.
MKV vs MP4 at a glance
| MKV | MP4 | |
|---|---|---|
| Type | Video container (any codec) | Video container (H.264 + AAC) |
| Compression | Depends on codec inside | Lossy, very efficient |
| Audio | Yes (multiple tracks) | Yes (AAC) |
| Compatibility | Media players only — not browsers, phones, or most editors | Universal — every device, browser, and editor |
| Best for | OBS recordings, archiving, multi-track video | Sharing, social media, editing, playback anywhere |
About the formats
MKV Matroska Video
MKV (Matroska) is a flexible open container that can hold virtually any codec plus multiple audio, subtitle, and chapter tracks. It's the format of choice for OBS recordings and media archiving, but browsers, phones, and most editing software don't accept it directly.
MP4 MPEG-4 Part 14
MP4 is the most widely supported video format in the world. Built on the H.264 codec with AAC audio, it plays on every phone, browser, TV, and editing app, and offers an excellent balance of quality and file size. When in doubt, MP4 is the safe choice for sharing video.
Frequently asked questions
Does the converter keep subtitles and multiple audio tracks?
No — MP4 output uses the first video and audio track; embedded subtitle tracks and secondary audio are dropped. If you need subtitles, extract them separately before converting.
Can I convert OBS recordings this way?
Yes — this is exactly the recommended OBS workflow: record to MKV so a crash can't corrupt the file, then convert to MP4 for editing and sharing. (OBS's own remux feature works too, but this converter also lets you trim, resize, and compress in the same step.)
Is this MKV to MP4 converter really free?
Yes — completely free, with no watermarks, no sign-up, and no conversion limits. The tool is supported by ads on this page, so the converter itself never asks you for anything.
Are my files uploaded to a server?
No. This converter runs entirely in your browser using WebAssembly (a browser build of FFmpeg). Your MKV file never leaves your device — nothing is uploaded, stored, or seen by us, which also makes it safe for private or confidential files.
Is there a file size limit?
There's no hard limit. Because conversion happens on your own device, the practical ceiling is your browser's memory — files up to a few hundred megabytes work well on most computers. Very large files may be slow or fail on low-memory devices.
Why does the first conversion take a moment to start?
The first time you convert, your browser downloads the conversion engine (about 31 MB) once. It's cached after that, so later conversions start instantly — and they keep working even offline.
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