Free MKV to MP4 Converter
Convert MKV files to MP4 for phones, TVs, editors and every platform. Smart mode remuxes H.264 clips losslessly in seconds and re-encodes the rest to H.264 — all in your browser, with no upload and no signup.
Drag & drop your MKV file here
.mkv up to 500 MB · H.264 clips convert losslessly in seconds · processed locally, never uploaded
Convert MKV to MP4 in 3 Steps
From "format not supported" to universal playback in under a minute.
Upload your MKV file
Drop in any .mkv up to 500 MB — HD downloads, screen recordings, course videos, anything.
Pick a quality preset
Smart mode detects your codecs: H.264 + AAC clips are remuxed losslessly; other codecs re-encode using your preset.
Convert and download
Download a standard MP4 that plays on iPhone, Android, smart TVs, editors and every platform.
Why people convert MKV to MP4
Watch on your phone
Neither iPhone nor Android plays MKV natively. Convert to MP4 and the file opens in the built-in player or gallery — no third-party app.
Smart TV & streaming sticks
MP4 is the most universally supported format on TVs, Apple TV and set-top boxes. Play straight from USB or over your local network.
Import into editors
Premiere, Final Cut and Resolve have shaky MKV support. Converting to MP4 avoids import failures and timeline errors before you edit.
Upload to platforms
Course platforms, knowledge bases and collaboration tools accept MP4 nearly everywhere — MKV frequently gets rejected.
MKV vs MP4 — What's the Difference?
Both are containers — the quality lives in the codecs inside. MP4 simply plays everywhere.
| MKV (Matroska) | MP4 (MPEG-4) | |
|---|---|---|
| Device compatibility | Good in desktop players; limited on phones and TVs | Natively supported by almost every device and platform |
| Subtitle tracks | Multiple soft subtitle tracks, selectable | Limited — usually needs hardcoding into the picture |
| Audio tracks | Multi-track, multi-language | Typically keeps the primary track |
| Codec support | Nearly everything (H.264, H.265, AV1, FLAC…) | All majors; H.264 has the widest support |
| Best for | HD movie storage, multi-language media | Sharing, playback, editing, uploads |
MKV to MP4 FAQ
Is this MKV to MP4 converter free?
Yes — completely free with no signup and no watermark on the output. Conversion runs in your browser, so there are no server costs to pass on.
Will converting reduce quality?
Often not at all. If your MKV already contains H.264 video (most downloads do), the tool remuxes it into an MP4 container without re-encoding — the video stream is bit-identical. HEVC or VP9 files are re-encoded to H.264; at the High or Very High preset the difference is virtually invisible.
What about subtitles in my MKV?
Embedded soft subtitle tracks are dropped — MP4's soft-subtitle support is inconsistent across players. If you need burned-in captions, hardcode them first, then convert. The main audio track is kept.
Can it convert H.265/HEVC MKV files?
Yes. HEVC video is re-encoded to H.264, which also makes the result playable on older devices that don't support HEVC at all.
Why is one file instant and another slow?
H.264 + AAC files are stream-copied — the video is never touched, so it finishes in seconds regardless of length. Other codecs require a real decode-and-re-encode pass, which takes longer and uses your selected quality preset.
What's the maximum file size?
Up to 500 MB. Everything is processed in your browser's memory, so very large movie files can exhaust the tab — for feature-length films, split the file first with the free video splitter, then convert the parts.
Will my file be uploaded to a server?
No. The conversion runs entirely in your browser using WebAssembly. Your MKV never leaves your device — nothing is uploaded, queued or stored.
Will the MP4 play on smart TVs?
Yes. The output is standard H.264 MP4 (with faststart for instant playback), which works on virtually every TV, streaming stick, console and mobile device.
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Add Watermark to Video
Brand your converted clip — add a watermark to video locally and free.
Make your MKV play everywhere
Drop in an MKV, pick a preset, and download a universal MP4 — lossless when possible, private always.