A free MKV to MP4 converter that turns MKV videos, like OBS recordings, into MP4s in your browser, instantly when it can.
Drop your MKV videos, like OBS recordings, and get MP4s. Most copy in under a second, with nothing lost.
Your videos
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The video and sound are copied into the new format as they are, when it takes them: nothing is lost, and it takes a moment. Otherwise they're re-encoded to look the same.
Convert
Add a video to convert.
Everything happens in this browser, with its own video encoders, so your videos never leave your computer. There's no size limit but your computer's memory.
This free MKV to MP4 converter turns MKV videos, like OBS recordings, into MP4s, in your browser. Most are copied into an MP4 in under a second, with nothing lost.
MKV is great for recording and awkward for sharing: phones, editors and sites often won't take it. Nothing is uploaded.
Here's why OBS records MKV, when it's instant, and how it compares with CloudConvert.
TL;DRKey takeaways
What is an MKV to MP4 converter?
An MKV to MP4 converter moves a video from the Matroska format, MKV, into MP4, the format every phone, editor and site takes.
MKV and MP4 can both hold H.264 and HEVC video, so converting is usually just a new box around the same picture.
Why OBS records MKV
OBS recommends MKV for recording, since an MKV isn't lost when a recording stops badly, like in a crash. An MP4 that doesn't finish can't be opened.
OBS's own Remux Recordings, in its File menu, turns an MKV into an MP4 too. This converter does the same in your browser, for a recording on any computer.
When it isn't instant
An MKV can also hold video or sound MP4 doesn't take, like VP9 video or FLAC sound. The file list tells you which way each video will go before you convert.
Those are re-encoded to H.264 and AAC, looking the same, in about 12 seconds a minute of 1080p on my Mac.
Compared with CloudConvert
I ran the same 10-second files through this converter and through CloudConvert, a popular online converter, on September 30, 2026. The score is how alike the result looks to the original, where 1 is identical:
- This converter
- Under a second, copied, nothing lost
- CloudConvert
- 6.1 s with the upload, re-encoded, score 0.990
Copying is faster than any re-encode, and keeps the recording exactly as it was.
CloudConvert's servers re-encode with x264, the best H.264 encoder, so its files came out about a quarter smaller at a similar score. This converter uses your device's own encoder, copies when it can, and never uploads your video.
Nothing is uploaded
Most online converters send your video to their server and send back the result. This one converts in your browser, with the video encoders built into it.
So your video never leaves your computer, there's no upload to wait for, and there's no size limit but your computer's memory.
Who is the MKV to MP4 converter for?
It's for anyone recording with OBS:
- Video resizer – creators posting one video to TikTok, Reels and YouTube
- Video caption generator – anyone adding captions before posting
- Screen recorder – people recording tutorials and demos
- MP4 to MP3 converter – podcasters turning video into an audio feed
Streamers use it to post clips from their recordings.
More free video tools
Here are my other video converters, and two for what comes next:
- Video converter – any video to MP4, WebM, MOV or GIF
- Compress video – smaller videos, or a size you set
- MOV to MP4 – iPhone and Mac videos that play everywhere
- WebM to MP4 – browser recordings that play everywhere
- Video to GIF – a short loop for chats and slides
- GIF to MP4 – a GIF as a video, a fraction of the size
- Video resizer – any video in TikTok, Reels or YouTube's size
- MP4 to MP3 converter – just a video's sound
They're all free, in your browser, with no watermark.
MKV to MP4 converter FAQs
Questions about the mKV to MP4 converter? Here's what to know.
An MKV to MP4 converter moves a video from the MKV format into MP4, which phones, editors and sites take.
Most MKVs are copied in under a second, with nothing lost.
OBS recommends MKV because the recording isn't lost if it stops badly, like in a crash.
An MP4 that doesn't finish can't be opened.
Not when it's copied: the picture and sound stay exactly as they were.
It's re-encoded only when the MKV holds something MP4 doesn't take.
Yes, the MKV to MP4 converter is free, with no account, no watermark and no limit on files.
It runs in your browser, so it costs nothing to run.
No, the MKV to MP4 converter converts your videos in your browser.
They never leave your computer.
I did.
I'm Navid Moazzez, and the MKV to MP4 converter is one of my free tools on navid.me.
Read more about me.
Navid Moazzez
AI business strategist & AI OS builder
Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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