Convert MKV to MP4
Convert MKV to MP4 on your device. Choose your file, convert, and check the result before sharing.
Drop the mkv file
Add your MKV video by dragging it in or browsing. It stays on this device.
Confirm MP4
The video is re-encoded as MP4 using an encoder running in this tab.
Download
The MP4 file saves straight back - no upload, no queue, no copy kept.
Why convert here, not there
No upload, ever
Cloud video tools take your mkv onto their disks. This one keeps it in your tab.
Local conversion
There is no file-upload step. Click Convert to start; the engine may need to load before conversion begins.
No account, no daily cap
No queue position, no throttling, no watermark burned into the mp4.
The two formats, briefly
| MKV | MKV is a container that can hold several types of video, audio and subtitles. A conversion may not preserve every track or attachment. | |
|---|---|---|
| MP4 | MP4 is a container. This converter writes H.264 video and AAC audio when an audio track is present; target-player support still needs checking. | |
When you need this
- Convert MKV when your target app asks for MP4 or does not decode the codecs in the source. This tool re-encodes rather than simply renaming the file; test playback before discarding the original.
MKV vs MP4: what changes
| MKV | MP4 | |
|---|---|---|
| Kind | Video | Video |
| Compression | Depends on source encoding | Depends on output encoding |
| Typical size | Depends on the file and encoding settings. | Measure the exported file; it may be larger. |
| Opens on | Check the source in your app and browser. | Check the downloaded file in the receiving app. |
| Best for | Keep the original as your source. | MP4 workflows, subject to the limits below. |
Keep the original. Compare the exported file before sharing or replacing it.
Tested on this tool
On 3 November 2026 we ran a synthetic test file through this converter: an 8-second, 640x480 H.264 MKV (917 KB) carrying two AAC audio tracks and one SubRip subtitle track. The output was a 773 KB MP4 - H.264 video plus one AAC audio track, 8.04 seconds - and the downloaded file decoded cleanly when we checked it.
- Only the first audio track came through; the second audio track was not in the output.
- The subtitle track did not carry over. If you need subtitles, keep them as a separate file.
- The video is re-encoded, not copied, so expect a quality shift from the original.
One small synthetic file is not every MKV. HEVC, ProRes and the other codecs an MKV can hold were not part of this test, and a phone browser can hit memory limits before a desktop does.
Good to know
- Balanced is the default H.264 setting. High and Max use less aggressive compression, but the result is still re-encoded and can be larger than the source.
- First use downloads the audio/video engine (about 30 MB). The input cap is 2 GB, but available browser memory can run out below that.