Convert Always

Runs on your device

MKV to MP4 converter

Convert MKV files to MP4 straight in your browser. Drop the file in, download the MP4 version, and nothing is uploaded to a server along the way.

Drop files here

Up to 20 files, 100.0 MB each. Conversion happens on your device — nothing is uploaded.

What is MKV?

Matroska is an open container designed to hold anything: multiple video and audio tracks, subtitles, chapters and attachments in a single file.

An open-source project started in 2002.

  • Unlimited tracks — multi-language audio and subtitles in one file
  • Chapters, attachments and rich metadata
  • Codec-agnostic and fully open

What is MP4?

MP4 is the universal video container, almost always carrying H.264 video with AAC audio. If a device plays video at all, it plays MP4.

Standardised by MPEG in 2001, based on Apple's QuickTime container.

  • The most compatible video format in existence
  • Hardware-accelerated decoding on virtually every chip
  • Streams progressively, so playback starts before the download finishes

Why convert MKV to MP4?

  • MP4 is the better fit for sharing, uploading and playing video anywhere, while MKV is built for media libraries that need multiple audio tracks and subtitles.
  • It sidesteps the main drawback of MKV: browsers and most phones will not play it natively.
  • You gain the most compatible video format in existence.
  • Compatibility improves where it counts: Every browser, phone, smart TV, console and editor.

Quality and file size after conversion

Expect a much smaller file. MP4 re-encodes the content and drops information it judges imperceptible, which is exactly why the result is a fraction of the MKV original. Keep the MKV master if you may need to edit or re-export later.

Compatibility

MKV opens in VLC, Plex, Kodi, MPV, Android with the right player. MP4 opens in Every browser, phone, smart TV, console and editor.

If the file has to work for someone else, choose the format their software already understands rather than the one with the best specification.

Limitations to know about

  • MP4 is lossy — the conversion is one-way and re-editing the output repeatedly will degrade it.
  • H.264 is less efficient than modern AV1 or HEVC
  • Licensing costs apply to commercial encoders

When to keep MKV instead

MKV is still the right choice for media libraries that need multiple audio tracks and subtitles. Keep the original alongside the converted copy whenever you might need to re-export at a different size or quality — conversion is quick, but recovering discarded detail is impossible.

How to convert MKV to MP4

  1. 1

    Drag your MKV file onto the drop zone above, or click to browse. Up to 20 files can be queued at once.

  2. 2

    MP4 is already selected as the output format — change it in the dropdown if you need something else.

  3. 3

    Press Convert and watch the per-file progress bar.

  4. 4

    Download the MP4 result, or grab everything as a single ZIP when you converted a batch.

Frequently asked questions

Is this MKV to MP4 converter free?

Yes. Every conversion on Convert Always is free, with no account, no watermark and no daily download cap. The site is funded by advertising rather than subscriptions.

Are my MKV files uploaded to a server?

No. MKV to MP4 runs entirely inside your browser using WebAssembly, so the file never leaves your device. You can even disconnect from the internet after the page loads.

Will converting to MP4 reduce the quality?

Expect a much smaller file. MP4 re-encodes the content and drops information it judges imperceptible, which is exactly why the result is a fraction of the MKV original. Keep the MKV master if you may need to edit or re-export later.

Can I convert several MKV files at once?

Yes. Add up to 20 files to the queue, convert them in one pass and download the results individually or bundled into a single ZIP archive.

What is the maximum MKV file size?

Files up to 100 MB each are accepted. Browser-side conversions are limited mainly by your device's memory, so very large video files convert faster on a desktop than on a phone.

Does it work on mobile?

Yes. The converter is built mobile-first and works in Safari and Chrome on phones and tablets. Heavy media conversions are slower on mobile hardware but still run locally.

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