Convert MKV to MP4
Convert Matroska MKV videos to universal MP4 format. Free, in your browser, no file uploads.
.mkv · up to 100 MB
Why convert MKV to MP4
From anime container to universal format
Universal compatibility
From MKV to MP4: compatible with any player, TV, phone, or social network without installing anything.
Guaranteed privacy
Your video never leaves your device. Local conversion with FFmpeg.wasm, no uploads.
No visible quality loss
H.264 CRF 23 re-encoding: visual quality virtually identical to the original.
No extra software needed
No need for VLC, HandBrake, or MKVToolNix. Everything runs in the browser, nothing to install.
How it works
Three steps, no hassle
Select your MKV file
Drag or select your .mkv file — a movie, TV show, anime, or recording. No registration required.
Local H.264 re-encoding
FFmpeg.wasm re-encodes the video with H.264 and audio with AAC in your browser. Your file is never uploaded to any server.
Download your MP4
The resulting MP4 is compatible with any player, social network, or device. Ready to share or edit.
FAQ
Got questions?
MKV (Matroska Video) is an open-source container format created in 2002 by Steve Lhomme and the Matroska team. Unlike MP4, MKV can store multiple audio tracks, multiple subtitle tracks, chapters, and advanced metadata in a single file. It is enormously popular in the anime community and high-definition movie distribution precisely because of this flexibility.
MP4 has universal compatibility: it works in all players (Windows Media Player, VLC, QuickTime), mobile devices (iPhone, Android), smart TVs, gaming consoles, and social media platforms (YouTube, Instagram, TikTok). MKV is great for storage but doesn't always play without installing additional software.
Subtitles embedded in the MKV may be lost during conversion, as MP4 has limited support for the most common MKV subtitle formats (ASS/SSA). If you need to preserve subtitles, use the burn-in option to permanently embed them into the video image.
By default, the first audio track from the MKV file is used. If your MKV has multiple languages (for example, Japanese and English), the first track found will appear in the MP4. To choose a specific audio track, command-line FFmpeg is recommended.
The conversion re-encodes video with H.264 (CRF 23) and audio with AAC. The resulting size is generally similar to or slightly smaller than the original, depending on the MKV's original codec. If the MKV already uses H.264, re-encoding may slightly increase size; if it uses H.265 or AV1, the MP4 could be somewhat larger.
Time is proportional to video length and device performance. As a reference, a 1-hour video typically takes 1-3 minutes of processing per minute of video on a modern computer. The first time you use the tool, the FFmpeg engine (~25 MB) downloads once and is cached for future use.
MKV to MP4: Matroska format history (2002, Steve Lhomme), MKV vs MP4 container comparison, H.264/H.265 codec support, and anime community adoption
The Matroska format (MKV) was created in 2002 by Steve Lhomme as an open alternative to the proprietary container formats of the era (Microsoft's AVI, Apple's MOV). The name references Russian matryoshka nesting dolls, symbolizing the format's ability to nest multiple multimedia streams in a single file. Matroska is based on EBML (Extensible Binary Meta Language), which allows it to adapt to new codecs and features without breaking backward compatibility. The full format specification is public and open source, which has encouraged widespread adoption.
The anime community and high-definition content distributors adopted MKV as the de facto standard for concrete technical reasons: the ability to include multiple audio tracks (dubs in multiple languages), multiple subtitle tracks in ASS/SSA format (with advanced typography and effects), navigable chapters, and complete metadata. An MKV file of an anime series can contain the original Japanese audio, English and Spanish dubs, subtitles in five languages, and series artwork — all in a single file. This richness makes it incompatible with basic players that only understand the limited MP4 subset.
The technical comparison between MKV and MP4 is fundamentally a comparison of containers, not codecs. Both can contain the same video codecs (H.264, H.265/HEVC, AV1, VP9) and audio (AAC, AC3, DTS, FLAC). The difference lies in container features: MP4 is more limited in subtitle types and tracks, but has native support on virtually all operating systems and devices without additional software. Converting MKV to MP4 does not degrade video quality if the same codec is used — only the container file changes. However, if the MKV uses H.265 or AV1 and is re-encoded to H.264 for MP4, there will be a slight loss in compression efficiency.