MKV to MP4 Converter
Convert Matroska MKV video files to universally compatible MP4 online for free. H.264 encoding. No software needed. Up to 100 MB.
Drop your MKV file hereTap to choose your MKV file
or
Also supports MOV, AVI, WebM, WMV, FLV • Max 100 MB
How to Convert MKV to MP4
Upload
Drag and drop your MKV video into the converter above, or click Choose MKV File to browse your device.
Convert
Click Convert to MP4. Our server re-encodes your video with H.264 + AAC for universal playback. Takes 30 seconds to 2 minutes.
Download
Click Download MP4 to save the converted video. That's it — no registration, no email required.
Convert MKV to MP4 on Any Device
On Windows 10/11
Windows can play some MKV files through the built-in Movies & TV app, but support is inconsistent. MKV files with VP9 video, FLAC audio, or multiple subtitle tracks often fail to play correctly. Windows Media Player has even more limited MKV support. If you need to share videos, upload to web platforms, or ensure reliable playback, converting to MP4 (H.264 + AAC) is the permanent solution that works everywhere without codec issues.
On Mac
macOS has no native MKV support — QuickTime Player cannot open MKV files. You need to install VLC or IINA for playback. Even with third-party players, MKV files cannot be previewed with Quick Look, used in iMovie, or shared via AirDrop without issues. Converting MKV to MP4 makes your videos work with every macOS application and sharing method natively.
On iPhone / iPad
iOS does not support MKV files natively. The Files app cannot preview them, and the Photos app cannot import them. VLC for iOS can play MKV, but you lose the ability to share videos via Messages, AirDrop, or social media directly. Converting to MP4 gives you full iOS integration — playback in all apps, easy sharing, and compatibility with every platform you might upload to.
On Smart TVs & Streaming Devices
Smart TVs from Samsung, LG, and Sony have varying MKV support. Basic MKV files with H.264 video may play, but files with multiple audio tracks, subtitle streams, or newer codecs like VP9, AV1, or DTS audio often cause playback failures. Roku, Apple TV, and Chromecast also have limited MKV support. MP4 with H.264 is the safest format for television playback across all brands and streaming devices.
What is MKV?
MKV (Matroska Video) is an open-source, free container format created in 2002 by Steve Lhomme. Named after Russian Matryoshka nesting dolls, it was designed to hold virtually anything: unlimited video, audio, subtitle, and chapter tracks in a single file.
MKV supports every major video codec — H.264, H.265, VP9, AV1, MPEG-4, and more — along with audio codecs like AAC, FLAC, DTS, Dolby TrueHD, and Opus. It can embed SRT, SSA/ASS, and PGS subtitles, chapter markers for scene navigation, and rich metadata including cover art.
The main drawback of MKV is limited device compatibility. While media center software (VLC, Plex, Kodi) handles MKV perfectly, most phones, tablets, smart TVs, web browsers, and social media platforms have limited or no MKV support. MKV is ideal for archiving and media libraries, but not for sharing.
What is MP4?
MP4 (MPEG-4 Part 14) is the international standard video container format, published as ISO/IEC 14496-14. It was derived from Apple's QuickTime MOV format in 2001, using the same atom/box architecture for organizing video, audio, and metadata.
MP4 supports H.264 and H.265 video with AAC audio, and includes the faststart flag (moov atom at the beginning) for instant web playback without buffering. It's the recommended upload format for YouTube, Instagram, TikTok, Facebook, and every major platform.
The defining strength of MP4 is universal compatibility. Every computer, phone, tablet, smart TV, gaming console, web browser, and media player manufactured in the last 15 years can play H.264 MP4 files. When you need a video that works everywhere without question, MP4 with H.264 is the safe choice.
MKV vs MP4: Quick Comparison
| Feature | MKV | MP4 |
|---|---|---|
| Developer | Matroska.org (2002) | ISO/MPEG (2001) |
| License | Open source (LGPL) | ISO standard (patented codecs) |
| Video codecs | H.264, H.265, VP9, AV1, MPEG-4, virtually any | H.264, H.265, AV1 |
| Audio codecs | AAC, FLAC, DTS, TrueHD, Opus, AC-3, PCM | AAC, MP3, AC-3 |
| Subtitle support | SRT, SSA/ASS, PGS, VobSub (unlimited tracks) | Limited (tx3g text only) |
| Multiple audio tracks | Unlimited | Supported (limited) |
| Chapter markers | Full support | Basic support |
| Windows playback | Partial (codec dependent) | Native (H.264) |
| macOS playback | Requires VLC/IINA | Native (QuickTime) |
| Smart TVs | Partial / unreliable | Universal |
| Web browsers | Not supported | All browsers (H.264) |
| Best for | Archiving, media centers, Plex/Kodi | Sharing, web, universal playback |
Understanding MKV to MP4 Conversion Quality
MKV and MP4 are both containers — wrappers that hold video and audio streams. Quality is determined by the codec inside (H.264, HEVC, VP9), not the container itself. The same H.264 video looks identical whether it's in an MKV or MP4 file.
If your MKV file already contains H.264 video and AAC audio, the conversion can be a remux — simply copying the streams into an MP4 container with zero quality loss. This is the fastest and best-quality option. When the MKV contains codecs not supported by MP4 (VP9, FLAC, DTS), re-encoding is required.
Our converter uses FFmpeg with H.264 encoding at CRF 23 (Constant Rate Factor), which produces quality that's indistinguishable from the original for most content. CRF 23 scores approximately VMAF 93–96 — well above the threshold where differences become visible. Audio is encoded as AAC at 192 kbps for transparent quality.
The -movflags +faststart flag moves the metadata to the beginning of the file so web browsers can start playback immediately without downloading the entire file first. The -pix_fmt yuv420p flag ensures compatibility with every device and browser.
Why Convert MKV to MP4?
Universal playback
H.264 MP4 plays on every device manufactured in the last 15 years: Windows PCs, Mac, iPhones, Android phones, smart TVs (Samsung, LG, Sony), gaming consoles (PS5, Xbox), and all web browsers. MKV fails on many of these platforms, especially when it contains VP9 video, FLAC audio, or multiple tracks.
Smart TV & streaming compatibility
MKV files are the most common cause of "format not supported" errors on smart TVs. Even when a TV technically supports MKV, files with DTS audio, multiple subtitle tracks, or high-bitrate HEVC often fail. Converting to MP4 eliminates all playback issues on televisions and streaming devices like Roku, Chromecast, and Apple TV.
Social media & web uploads
YouTube, Instagram, TikTok, Facebook, and Twitter all recommend MP4 with H.264 for uploads. None of these platforms accept MKV files. Converting to MP4 is required before uploading to any social media platform or embedding video on a website.
Mobile device sharing
Neither iOS nor most Android gallery apps handle MKV natively. If you want to share a video via Messages, WhatsApp, AirDrop, or email, MP4 is the only format that works reliably across all messaging platforms and operating systems.