Why does my TV or phone refuse to play MKV?

MKV (Matroska) is a flexible container that many smart TVs, iPhones and stock players do not fully support. MP4 is the universally accepted format that plays everywhere, so converting clears "unsupported file" errors on the first try.

Does converting MKV to MP4 re-encode the video?

When the video inside is already H.264 or H.265 it can often be repackaged quickly with no quality change; otherwise it is re-encoded for compatibility. Either way the original resolution and frame rate are kept.

Will subtitles inside the MKV be kept?

Soft subtitle tracks embedded in MKV are not carried into the MP4. If you need captions, convert the video and load a separate .srt subtitle file in your player, or burn the subtitles in beforehand.

My MKV has several audio tracks — what happens?

MKV movie files often bundle multiple audio tracks, such as different languages or commentary. The MP4 keeps the primary track and turns it into the standard stereo audio that every phone, TV and browser plays.

Why are MKV files so common for movies?

MKV is the favourite container for high-quality video because one file can hold HD or 4K video, several audio languages and subtitle tracks together. That richness is exactly what stock players struggle with — MP4 trades it for universal playback.

Will the MP4 be much larger or smaller?

The size stays close to the original when the video is repackaged rather than re-encoded. A 4K HEVC MKV re-encoded to H.264 may grow somewhat, while a straightforward repackage keeps the file roughly the same size.

Can I stream the MP4 to my TV after converting?

Yes. MP4 is the format smart TVs, Chromecast, Apple TV and DLNA media servers expect, so the converted file streams cleanly where the original MKV would not appear in the list or would stutter.

Convert MKV to MP4 Online

Convert MKV for playback on TVs, phones and any app that refuses to open Matroska files.

or drag & drop them here · images, video, audio and documents · up to 2 GB

How to convert MKV to MP4

Click "Choose Files" and select your MKV file, or drag & drop it onto the page.
Make sure MP4 is selected as the target format.
Click "Convert" and wait a few seconds.
Download your new MP4 file.

Why Converters.live?

Free and unlimited — convert as many MKV videos to MP4 as you need, no daily limits.
Files up to 2 GB, processed with the same FFmpeg engine professional tools use, keeping video and audio in sync.
Your video files are deleted from the server immediately after conversion — nothing is stored.

Frequently asked questions

Why does my TV or phone refuse to play MKV?: MKV (Matroska) is a flexible container that many smart TVs, iPhones and stock players do not fully support. MP4 is the universally accepted format that plays everywhere, so converting clears "unsupported file" errors on the first try.
Does converting MKV to MP4 re-encode the video?: When the video inside is already H.264 or H.265 it can often be repackaged quickly with no quality change; otherwise it is re-encoded for compatibility. Either way the original resolution and frame rate are kept.
Will subtitles inside the MKV be kept?: Soft subtitle tracks embedded in MKV are not carried into the MP4. If you need captions, convert the video and load a separate .srt subtitle file in your player, or burn the subtitles in beforehand.
My MKV has several audio tracks — what happens?: MKV movie files often bundle multiple audio tracks, such as different languages or commentary. The MP4 keeps the primary track and turns it into the standard stereo audio that every phone, TV and browser plays.
Why are MKV files so common for movies?: MKV is the favourite container for high-quality video because one file can hold HD or 4K video, several audio languages and subtitle tracks together. That richness is exactly what stock players struggle with — MP4 trades it for universal playback.
Will the MP4 be much larger or smaller?: The size stays close to the original when the video is repackaged rather than re-encoded. A 4K HEVC MKV re-encoded to H.264 may grow somewhat, while a straightforward repackage keeps the file roughly the same size.
Can I stream the MP4 to my TV after converting?: Yes. MP4 is the format smart TVs, Chromecast, Apple TV and DLNA media servers expect, so the converted file streams cleanly where the original MKV would not appear in the list or would stutter.

About MKV and MP4

Key things to know before you convert MKV to MP4:

MKV

MKV (Matroska) holds anything: multiple audio tracks, subtitles, chapters, any codec. Great for archiving movies, bad for sharing — many apps cannot open it.

MP4

MP4 with H.264 is the universal video format: phones, TVs, browsers, editors and messengers all play it. When in doubt, send MP4.

Related conversions

WEBM→MP4 MOV→MP4 AVI→MP4 GIF→MP4 WMV→MP4 FLV→MP4 M4V→MP4 MKV→MP3