MKV vs MP4: Differences and Which to Use

MKV and MP4 are both containers: they hold the same kinds of video and audio (usually H.264 or H.265 with AAC), so quality is the same. The difference is in what else they can hold and where they play. MKV can carry many audio and subtitle tracks and survives a crash mid-recording; MP4 plays on almost every device, editor and platform. So record in MKV, and share in MP4.

More on this topic: Video formats, codecs and numbers, every guide in one place.

Here's the comparison, why OBS recommends MKV, what YouTube accepts, and how to turn an MKV into an MP4 in seconds without re-encoding.

The short answer

Quality is identical when the codecs are the same; MKV and MP4 are just containers. Use MKV for recording (OBS recommends it, because an MKV isn't corrupted if the recording stops unexpectedly) and for files with several audio or subtitle tracks. Use MP4 for editing, sharing and uploading: MP4 is on YouTube's list of supported formats and MKV isn't. Convert by remuxing: ffmpeg -i in.mkv -c copy out.mp4, or OBS's File > Remux Recordings.

Key takeaways

• Same codecs inside = same quality. MKV vs MP4 is about features and compatibility.
• MKV: many audio and subtitle tracks, chapters, crash-resistant recording.
• MP4: plays almost everywhere, from phones and browsers to editors and social platforms.
• Remuxing MKV to MP4 copies the streams without re-encoding: fast and lossless.
• Subtitle tracks in SRT or ASS don't copy into MP4 as they are; convert or export them separately.

What is the difference between MKV and MP4?

The difference between MKV and MP4 is the container: how the video, audio and extra data are packaged, not how they're compressed. MKV (Matroska) is an open, flexible container; MP4 (MPEG-4 Part 14) is a standard container derived from Apple's QuickTime format.

Is MKV better quality than MP4?

No. MKV isn't better quality than MP4: if both hold the same H.264 video at the same bitrate, the picture is bit-for-bit identical. Quality comes from the codec and bitrate. An MKV can hold lossless audio tracks or higher-bitrate streams, but an MP4 can hold the same video. When people say MKV looks better, they're usually comparing different encodes, such as a high-bitrate MKV and a compressed MP4.

Why does OBS record in MKV?

OBS recommends recording in MKV because it protects the file if the recording doesn't stop cleanly. OBS's recording guide says MKV is recommended in case of unforeseen issues, because it won't corrupt the whole file if there is no graceful stop. A standard MP4 writes key index information at the end, so a crash, power cut or full disk can leave a file that won't open.

OBS also makes the conversion easy: File > Remux Recordings turns MKV files into MP4 for your editor, and an advanced setting, Automatically remux to mp4, does it as soon as you stop recording. Some recorders offer fragmented MP4 or MOV as a middle ground, which also survives interruptions.

Can you upload MKV to YouTube?

MKV isn't on YouTube's list of supported file formats, which includes MOV, MP4, AVI, WMV, FLV, 3GPP, WebM, ProRes and others. Some people report that MKV uploads work anyway, but there's no reason to rely on it: remux to MP4 in a few seconds and upload a file YouTube recommends. For social platforms and messaging apps, MP4 is the format to use.

See the best export settings for YouTube for the rest of the upload settings, and MP4 vs MOV for the other common container choice.

How do you convert MKV to MP4 without losing quality?

You convert MKV to MP4 without losing quality by remuxing: copying the video and audio streams into a new container without re-encoding. It takes seconds, even for long files, as long as the codecs are ones MP4 supports (H.264, H.265 or AV1 video; AAC, MP3 or Opus audio).

If FFmpeg refuses to copy a stream, the codec isn't allowed in MP4 (for example, some PCM or AC-3 audio in older players, or PGS image subtitles). Re-encode only that stream: -c:v copy -c:a aac -b:a 192k. Note that by default FFmpeg keeps one video and one audio stream; the -map options above keep the rest.

What about the subtitles inside an MKV?

Subtitles inside an MKV are usually SRT or ASS tracks, and MP4 can't hold them as they are. Either convert them to MP4's text format while remuxing (the mov_text command above, which drops ASS styling), extract them to a separate file, or burn them into the picture. To pull a subtitle track out: ffmpeg -i in.mkv -map 0:s:0 subs.srt.

Once it's a separate file, you can tidy it in any text editor, convert it with the free SRT to VTT converter for web players, or burn it in; how to convert ASS to SRT and how to burn subtitles into a video cover both. QuickVeed's auto subtitles can also make new subtitles from the audio and export SRT or VTT in 32 languages.

How do you open an MKV file?

You open an MKV file with VLC, which plays it on Windows, Mac, Linux, iPhone and Android, along with every audio and subtitle track inside. Many smart TVs, media servers such as Plex, and Android video apps play MKV too. Apple's own apps are the usual exception: QuickTime Player and the iPhone's Photos app don't open MKV, so on Apple devices use VLC or remux the file to MP4.

In VLC, switch audio languages under Audio > Audio Track and subtitles under Subtitle > Sub Track. If subtitles are listed but don't appear, see VLC subtitles not showing.

Which should you use: MKV or MP4?

If a file is too big after remuxing, the container isn't the problem: lower the bitrate. The free video compressor re-encodes to a smaller MP4 in your browser, and video file size per minute shows what to expect.

Frequently asked questions

Is MKV or MP4 better?

Neither is better quality. MKV is better for recording and multi-track files; MP4 is better for editing, sharing and uploading.

Does converting MKV to MP4 lose quality?

Not if you remux (copy the streams). Re-encoding loses a little; remuxing loses nothing.

What about AVI files?

AVI is an older Microsoft container from 1992. YouTube accepts it, but browsers generally don't play it and it handles modern codecs poorly, so remux or convert AVI to MP4 the same way. See AVI vs MP4.

Can YouTube play MKV files?

MKV isn't on YouTube's list of supported formats. Remux it to MP4 before uploading.

Why does OBS use MKV?

Because an MKV recording stays readable if OBS or the computer crashes, while an interrupted MP4 can be unusable.

Can iPhone play MKV?

Not in the Photos app or QuickTime. Use VLC, or remux the file to MP4.

How do I keep all audio tracks when converting MKV to MP4?

Use ffmpeg with -map 0:v -map 0:a -c copy, which copies every video and audio stream.

Try it with your own video

Caption your recordings and translate them into 32 languages, then download SRT or VTT. Upload an MP4, check the transcript, and export the subtitle file. QuickVeed plans start at $18/month, and new accounts get a 14-day trial with 250 credits, no card needed. Sign up or see pricing.

Sources

Competitor details in this post were checked against these public pages in October 2026. Products and prices change, so confirm with each vendor before you decide.

• OBS knowledge base: standard recording output guide (MKV, remux)
• YouTube Help: supported YouTube file formats
• MDN: media container formats (WebM, MP4, Matroska)