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MKV to MP4 Converter

Convert MKV files to H.264 MP4 so they play on phones, TVs and editors that refuse Matroska files. Everything runs locally in your browser — no upload, no file-size queue.

MKV is a great archive format and a poor sharing format

Matroska files can hold many video, audio and subtitle tracks in one container, which makes MKV popular for archives and recordings. Playback is the problem: phones, smart TVs, game consoles and most editors either ignore MKV or support only some of the codecs it can contain. Converting to MP4 with the video to MP4 converter above produces a single H.264 video with AAC audio — a file that simply plays when you send, upload or edit it.

Know what does not carry over

An MP4 from this converter holds one video and its audio. Extra audio tracks and embedded subtitle tracks in the MKV are not copied, and the re-encode to H.264 is lossy, so treat the MKV as your master and the MP4 as the working copy. The maximum resolution you pick caps the output size; smaller sources are never enlarged. Other containers behave the same way here: MOV to MP4, WebM to MP4 and AVI to MP4 all use the same local engine.

Converted on your machine only

Nothing about your video leaves the browser tab. There is no upload step, no conversion queue and no copy of your file stored on a server.

Frequently asked questions

Why won't my phone or TV play MKV?

MKV (Matroska) is a flexible container that consumer devices support inconsistently. Many phones, TVs and editors skip it entirely, while MP4 with H.264 plays on virtually all of them.

My MKV has several audio tracks. Which one is kept?

The converter builds one MP4 with AAC audio. Multi-track files, such as recordings with separate commentary, can lose the extra tracks — verify the download and keep the MKV as your master copy.

Are subtitles from the MKV preserved?

No. Subtitle tracks inside the MKV are not copied into the MP4. If you need the subtitles, extract them first with a subtitle tool and keep them alongside the video.

The conversion failed. Why?

MKV can wrap almost any codec, including ones the in-browser engine cannot decode. Encrypted, damaged or exotic streams may fail; common H.264 and H.265 sources convert normally.

Is there a file size limit?

The file is processed on your device, so the practical limit is your machine's memory and patience rather than a server quota. Very large files convert more comfortably on a desktop browser.

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