Why convert MKV to MP4?
MKV is a fantastic archival container — it stores HD video, several audio tracks, multiple subtitle layers, chapters, and metadata in one file. The catch is that most consumer devices and platforms do not play MKV reliably: iPhones and iPads refuse it without a third-party app, Apple TV and many smart TVs only handle it intermittently, hardware media players hit codec mismatches, and Slack, Discord, and Twitter (X) reject MKV uploads outright.
MP4 is the universal alternative. Both containers can hold the same H.264 / H.265 / AV1 video and AAC audio, so a clean MKV → MP4 conversion is often a fast, lossless remux — the data is repackaged into the new container with the original quality intact, in a fraction of the time a re-encode would take.
File Converter Pro runs MKV → MP4 fully offline on Windows 10 and 11. There’s no upload of your 4 GB movie file to a third-party server, no per-task limit, and no watermark on the output. The same engine handles a single Blu-ray rip and a folder of TV-show episodes in one batch.
How to convert MKV to MP4 on Windows
- Install File Converter Pro. Install File Converter Pro from the Microsoft Store on Windows 10 or 11. The free trial supports MKV to MP4 conversion at full quality with no time limit per file.
- Drag your MKV files into the queue. Open the app and drag one MKV or an entire folder. Mixed resolutions, mixed codecs, and large 4K files are all accepted.
- Pick MP4 as the output format. Select MP4 in the output panel. Choose remux (fastest, no quality loss) when the source codec is already MP4-compatible. Pick re-encode with H.264 / H.265 / AV1 only when you also need a smaller file or a specific bitrate.
- Run the batch conversion. Click Convert. Files are processed locally — no upload. Output MP4s are saved next to the originals or to a folder you specify. A typical 1080p remux finishes in under a minute even on older laptops.
Batch conversion for big folders
If you have a folder of TV-show episodes, ripped DVDs, or a back-catalog of MKV recordings, batch processing is the whole point. File Converter Pro is built around the queue — drop a directory and every MKV inside (subfolders included if you opt in) is added in one shot.
- Process hundreds of episodes in a single run, with no per-task cap.
- Mirror the original folder structure on output, or flatten everything into one directory.
- Skip files that already have an MP4 sibling, or overwrite — your choice.
- Pause and resume the queue without losing finished conversions.
Quality settings that actually matter
MKV → MP4 is most often a remux — the audio and video streams are repackaged into the MP4 container without touching the encoded data. That’s the right choice for 90 % of conversions: it finishes in seconds, keeps the original quality bit-for-bit, and produces a file the same size as the source.
- Remux (default): when the source is H.264, H.265, or AV1 video with AAC audio. Lossless, near-instant.
- Re-encode H.264: when the target device only plays H.264 (older smart TVs, hardware players). Sets a CRF or bitrate target.
- Re-encode H.265: when you want a smaller file at the same quality. ~30-50 % size savings versus H.264.
- AV1: next-gen codec with the best compression, but encode time is 5-10× H.264. Pick when storage matters more than speed.
For audio, passthrough keeps the original AAC track untouched. Re-encode AAC at 128-256 kbps if the source is FLAC, AC-3, or DTS and your player can’t decode those. Subtitles can be kept as soft tracks (selectable in the player) or burned into the video.
Common issues and fixes
- Audio missing on iOS playback. The MKV had a DTS or AC-3 audio track that iOS can’t decode. Re-encode audio to AAC during the conversion.
- Subtitles disappear. Toggle “keep soft subtitles” in the output panel, or burn them into the video for guaranteed playback.
- File size unchanged. That’s expected for a remux — the goal was compatibility, not compression. Switch to re-encode H.265 if you also want smaller files.
- Frame skipping on a smart TV. The TV only supports H.264. Re-encode the video stream from H.265 to H.264 with a comparable CRF.
Related conversions
FAQ
Will converting MKV to MP4 lose video quality?
No, when you remux. Remux only repackages the streams into the new container, so quality stays bit-for-bit identical to the source. Quality only changes if you choose to re-encode the video stream.
Can File Converter Pro keep multiple audio tracks and subtitles?
Yes. The app lets you choose which audio tracks and subtitle layers to carry over to the MP4. Soft subtitles stay selectable in any modern player; you can also burn them into the video for guaranteed display.
How fast is MKV to MP4 conversion?
A 1080p remux usually finishes in seconds because no re-encoding happens. Re-encoding to a different codec (H.265, AV1) takes longer — figure 1× to 10× the video duration depending on the codec and your CPU.
Is MKV to MP4 conversion offline?
Yes. File Converter Pro runs the conversion entirely on your Windows PC. Nothing is uploaded — useful for movie files that web converters cap at 100 MB or 1 GB.
Ready to convert your MKV files?
Download File Converter Pro from the Microsoft Store, drop your MKV files into the queue and have universally compatible MP4s ready in seconds — fully offline, no watermark, no size cap.