Convert MKV to MP4 Online
Turn MKV files into MP4 directly in your browser using ConverterUp. There is no upload, no waiting in a queue, and no account required — your files stay on your device while WebAssembly does the work locally. Adjust quality and dimensions where supported, then download the result. The output keeps the visual fidelity you'd expect from a desktop app while running entirely in the browser tab.
Convert MKV to MP4 nowHow to convert MKV to MP4
Open the converter
Click the button to open the MKV to MP4 tool. It loads instantly — no install, no signup.
Drop your MKV file
Drag your MKV file into the upload area or click to browse. The file stays in your browser memory only.
Download MP4
The conversion runs locally and finishes in seconds. Click download to save the MP4 file to your device.
MKV vs MP4 at a glance
Key technical differences between the two formats, so you know what to expect before converting.
| Feature | MKV | MP4 |
|---|---|---|
| Type | Video container | Video container |
| Compression | — | Lossy |
| Audio track | Yes | Yes |
| Common codecs | H.264, HEVC, VP9, AV1, AAC, Opus, FLAC | H.264, H.265, AV1, AAC |
| Browser support | Partial | All browsers |
| Extensions | .mkv | .mp4 |
| MIME type | video/x-matroska | video/mp4 |
| Introduced | 2002 · Matroska | 2003 · MPEG (ISO/IEC 14496-14) |
What changes when you convert MKV to MP4
- MKV and MP4 are containers. The video and audio streams are re-encoded into codecs that MP4 supports (typically H.264, H.265, AV1), so you get a file that plays reliably rather than a simple rename.
- The audio track is carried over to the MP4 file, re-encoded if needed.
- Compatibility improves: MP4 opens in more browsers, apps and operating systems than MKV.
About MKV
MKV (Matroska) is an open container that can hold almost any video, audio and subtitle codec, with multiple audio tracks, chapters and subtitles in one file.
- Best for
- Movie and TV rips, multi-language videos, archiving with subtitles.
- Strengths
- Extremely flexible, open standard, keeps multiple tracks and subtitles.
- Limitations
- Not playable in Safari or on many phones and TVs without extra apps.
About MP4
MP4 (MPEG-4 Part 14) is the most widely supported video container. It typically holds H.264 or H.265 video with AAC audio and plays on virtually every phone, browser, TV and editor.
- Best for
- Sharing videos, uploading to social networks and YouTube, and playback on any device.
- Strengths
- Universal playback, good compression, streaming-friendly.
- Limitations
- Lossy codecs, so repeated re-encoding gradually reduces quality.
Frequently asked questions
Is the MKV to MP4 conversion really free?
Yes. ConverterUp is fully free, with no signup, no watermarks, and no daily quota for the MKV to MP4 converter. We support the project through unobtrusive ads.
Are my MKV files uploaded to a server?
No. Conversion runs in your browser using WebAssembly. The MKV bytes never leave your device, and we have no upload endpoint at all.
What is the maximum file size?
For MKV input, the soft cap is 50 MB for images and 500 MB for video. Practical performance depends on your device's RAM.
Will the MP4 file open everywhere?
Yes. MP4 is supported by every modern browser, operating system and most apps, so it is the safe choice for sharing.
Does converting MKV to MP4 keep the sound?
Yes. The audio track is kept and, if necessary, re-encoded into a codec that MP4 supports.
Related guide
How to Convert MP4 to GIF Free OnlineRelated conversions
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