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MKV to MP4 Converter

MKV files come from OBS recordings, downloads and rips — a great archival container that phones, TVs, editing apps and web uploaders routinely refuse. The good news: the video inside is almost always H.264 or HEVC, which MP4 carries natively, so this converter usually just rewrites the container without re-encoding — a multi-GB recording becomes an MP4 in seconds, at identical quality, without ever being uploaded.

  • No upload — files stay on your device
  • Works offline once loaded
  • Free forever, no signup, no watermark
Drop your {{ fromLabel }} file here, or tap to choose Converted to {{ toLabel }} on your device — nothing is uploaded
Reading the file…

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  • File {{ sourceSizeLabel }}
  • Duration {{ durationLabel }}
  • Resolution {{ resolutionLabel }}
  • Video codec {{ info.videoCodec || '—' }}

Instant conversion — the streams are copied, no re-encoding, no quality loss

This file needs a re-encode to become {{ toLabel }}. Your browser's hardware encoder does the work — expect roughly the video's playing time or less.

Heads up: this file is over 500 MB. It will still work — everything streams from disk — but a re-encode can take a while, especially on a phone.

{{ instant ? 'Copying streams into the new container…' : 'Re-encoding with your hardware encoder…' }} {{ progress }}%

Preview
  • Original {{ sourceSizeLabel }}
  • {{ toLabel }} file {{ resultSizeLabel }}

Video stream copied untouched — identical quality to the original.

The audio track used a codec this browser could not convert, so the output is silent.

How to use this tool

  1. Drop your MKV

    OBS recordings and downloads of any size work — the file streams from disk, so even 10 GB doesn't need to fit in memory.

  2. Convert — usually instantly

    H.264/HEVC video is stream-copied into MP4 untouched (you'll see an "Instant conversion" badge). Only unusual codecs like VP9-in-MKV trigger a real re-encode.

  3. Download the MP4

    It now imports into Premiere and DaVinci, uploads to editing and sharing sites, and plays on TVs and phones that rejected the MKV.

Questions people ask

Why won't my MKV file play or import anywhere?

MKV (Matroska) is a container many consumer apps never added support for — Premiere Pro historically refused it, iPhones and many TVs still do, and most web uploaders reject it. The video stream inside is usually completely standard; only the wrapper is the problem.

Why was my conversion instant?

Because the MKV's video was H.264 or HEVC and its audio AAC or MP3 — all codecs MP4 carries natively. The tool stream-copied them into a new container without decoding a single frame. That is also why the quality is bit-for-bit identical.

I record with OBS into MKV — is this the right workflow?

Yes, and it is a smart one: recording to MKV means a crash doesn't corrupt the whole file. Convert to MP4 here afterwards for editing (OBS's own "remux" feature does the same job — this tool is handy when you're on a different machine, or the file already left OBS).

What happens to multiple audio tracks and subtitles?

MP4 output keeps the primary video and primary audio track. Extra audio languages and embedded subtitle tracks from the MKV are not carried over — if you need those, keep the original MKV as your archive copy.

Is there a size limit? My recordings are huge.

No hard limit. The file is read as a stream, so multi-GB OBS recordings convert fine — and since stream-copying is basically fast file copying, even huge files finish quickly.

Is anything uploaded?

No. A server-based converter would spend an hour just uploading a big recording before it even started. Here the entire job happens on your own disk and CPU — that is the whole point.

Related tools

Free because it costs us nothing to run: your browser does the work, not our servers. Made by Dynamb Technologies — we build software for businesses.