How to Convert MKV to MP4 Without Losing Quality
MKV and MP4 are containers. If the video inside is H.264 or H.265 with AAC audio — the usual case — it can be moved into an MP4 without being re-encoded, so the quality is exactly the same.
Drop your MKV file
Press Convert
Download the MP4
Choose file
or drag & drop — video files
Free · Unlimited · No sign-up · Max 10 GB
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The Quick Way
Drop the MKV into the MKV to MP4 converter and press Convert. When the streams inside are allowed in MP4, they are copied bit for bit: the result is identical in quality and is ready in seconds. No settings are needed — the converter checks the codecs and chooses the copy automatically.
Why There Is No Quality Loss
Converting usually means decoding the video and encoding it again, which costs time and a little quality. Changing the container does not: the compressed video and audio are taken out of the MKV wrapper and written into an MP4 wrapper unchanged. This is called remuxing.
MP4 accepts H.264, H.265 (HEVC), AV1 and MPEG-4 video, and AAC, MP3 and AC-3 audio. An MKV holding those is remuxed. An MKV holding something else — VP9 video, or DTS, Opus or FLAC audio — has that stream re-encoded, at the source's resolution and frame rate.
What Is Kept and What Is Not
| In the MKV | In the MP4 |
|---|---|
| Video stream | Kept, same resolution, frame rate and bitrate |
| All audio tracks | Kept |
| Subtitle tracks | Not carried over — MP4 does not support the usual MKV subtitle formats |
| Attached fonts | Not carried over |
How to Tell Whether It Was Remuxed
- It finished within seconds of the upload (or instantly in the browser).
- The MP4 is almost exactly the size of the MKV.
- If it took minutes and the size changed, a stream had to be re-encoded.
Frequently Asked Questions
Is MKV to MP4 always lossless?
When the MKV contains codecs MP4 supports — H.264/H.265 video with AAC, MP3 or AC-3 audio — yes. Otherwise the unsupported stream is re-encoded.
Why does my MP4 have no subtitles?
MKV subtitle formats (SRT, ASS, PGS) are not supported inside MP4, so subtitle tracks are left out.
How big can the file be?
10 GB. Files up to 900 MB that can be remuxed are converted in your browser without an upload.
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Last checked: 2026-10-02