Convert MKV to MP4 — Offline
Drop one or more Matroska MKV files onto MiniMax Converter and get standard MP4s back. When the video and audio codecs are already MP4-compatible (H.264/H.265 + AAC), it stream-copies — fast and lossless, no re-encoding. When they aren't, it transcodes. Runs locally: no upload, no file-size limit, no watermark.
How to convert
- Drag your MKV file (or a folder of them) onto the MiniMax Converter window.
- Pick MP4 as the output format from the format chooser.
- Choose quality: leave it on stream-copy/auto for a fast lossless remux when codecs are compatible, or set a CRF or bitrate for transcoding.
- Click convert and save the MP4 next to your original.
Lossless when it can be, honest when it can't
If your MKV already holds an MP4-friendly codec pair (typically H.264 or H.265 video with AAC audio), the conversion is a pure stream copy — the bytes are repackaged into an MP4 container with zero quality loss and almost no CPU work. If the streams aren't MP4-compatible (e.g. VP9 video or FLAC/Vorbis audio), it transcodes with libx264 + AAC instead, which is a normal lossy re-encode. We tell you which path applies rather than pretending every conversion is lossless.
Batch a whole folder in parallel
Drop a folder of MKV episodes and they all convert in one pass — files run concurrently, not one at a time, so a season of recordings finishes far quicker than a serial tool. Remuxable files fly through at near-disk speed; only the ones that genuinely need transcoding cost real time. Everything runs through ffmpeg under the hood, the same engine the app uses for all audio and video work.
Why offline?
Online MKV-to-MP4 converters cap file sizes (often 100–500 MB), throttle your upload, and make you wait for a multi-gigabyte movie to travel to a server and back — frequently adding ads or watermarks. MKV files are commonly multi-GB Blu-ray rips or long recordings, exactly the kind those services choke on. Local conversion handles any size at SSD speed, and your files never leave your machine.
Questions and answers
Is MKV to MP4 lossless?
It can be. When your MKV's video and audio codecs are already MP4-compatible (H.264/H.265 + AAC), the app stream-copies them into the MP4 container with no re-encoding and no quality loss. If the codecs aren't MP4-compatible, it transcodes, which is a normal lossy re-encode.
Why is the conversion sometimes nearly instant and sometimes slow?
A near-instant result means a lossless remux — the streams were copied straight into the MP4 container. A slower run means the codecs had to be transcoded, which re-encodes the video and takes real CPU time proportional to the file's length.
Will it keep my subtitles and multiple audio tracks?
MP4 is more limited than MKV here. AAC/AC-3 audio tracks carry over, but MKV subtitle formats like SRT or ASS must be converted to MP4's mov_text or burned in, and some exotic tracks MP4 can't hold may be dropped. For full track control, use the Convert → More subtitle and audio-track tools.
Can it handle large MKVs over 4 GB?
Yes — there's no file-size cap. Conversion streams through ffmpeg, so memory use stays constant whether the file is 200 MB or a 40 GB Blu-ray rip. A lossless remux of a large file is limited mainly by your disk speed.
Related tools
Get MiniMax Converter
Cross-platform desktop app. Linux free for non-commercial use; Windows & macOS one-time €20 license. No subscription, no telemetry, no account.