Convert MKV to MP4
Few devices play MKV. If the contents are H.264 + AAC, swapping the container gives a lossless MP4 in seconds.
Settings
How to use
- 1
Add videos
Drop MP4, MOV, WebM, MKV and similar files. Several videos can be converted in turn with the same settings.
- 2
Choose the output format
MP4 (H.264), WebM (VP9), MOV or MKV. When the codec already matches, the stream is copied instead of re-encoded, which is very fast.
- 3
Convert and save
Save once the progress bar reaches 100%. Long videos take a while; keep the tab open.
About MKV
MKV (Matroska) is a general-purpose container that can hold any codec, plus subtitles and multiple audio tracks. iPhones, most TVs and video editors cannot play it, however.
If the video is H.264 and the audio AAC, the streams are moved into an MP4 without re-encoding. VP9 or AV1 video and Opus or FLAC audio are re-encoded. Subtitle tracks are not carried over to MP4.
Frequently asked questions
Are subtitles kept?
No. MKV subtitle tracks are not converted into the MP4.
What about multiple audio tracks?
Only the first audio track is converted.
What happens with HEVC MKVs?
If the browser can decode HEVC, it is re-encoded to H.264 for the MP4. On browsers that cannot decode it, loading fails.
Is quality lost?
Not when the codec matches, since it is copied. When re-encoding is needed, the Quality setting applies.
Help us improve the service
If a conversion fails, sending us the circumstances helps us track down the cause. Knowing which devices and formats fail most often, and how long processing takes, lets us revise the supported formats and fix the bugs behind them. If you don't mind, leaving this on is a real help.
What is sent
The tool you used and the settings you chose (output format, quality, etc.), your device specs (GPU, memory, core count), the input format with a rough size, how many files succeeded or failed and how long it took, and the error type and details when something fails.
What is never sent
The files themselves, file names, text, subtitles or prompts you add to a video, and IP addresses. The data goes only to this site's own server, never to a third-party service.