MKV to MP4 Converter
Convert Matroska (.mkv) files, from OBS recordings to downloaded clips, into MP4 with H.264 video and AAC audio so editors, phones and TVs that ignore MKV can open them.
Video Converter
or drop MP4, MOV, MKV … files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
Lower is better quality and a bigger file. 18 looks identical to the source, 23 is the default, 28 and above shows visible softening.
Frames per second. Keep the source rate unless a platform asks for a specific one; 15–20 fps is plenty for GIFs.
Only used for PowerPoint files and single still images: how long each slide or picture stays on screen.
Auto uses AAC for MP4/MOV and Opus for WebM. Copy keeps the original sound untouched when the new format supports it.
192 kbps is transparent for music; 128 kbps is enough for speech.
Width of the animation in pixels; height follows the aspect ratio. 480 px suits chats, 720 px or more gives a high-quality GIF but a much larger file.
GIF holds at most 256 colors. Fewer colors make a smaller file but cause banding on gradients and skin tones.
Mixes palette colors in a fine pattern to hide banding. Sierra gives the smoothest result; none gives the smallest file.
Whether the animation repeats endlessly or plays one time and stops.
Optional. Seconds (e.g. 75) or minutes:seconds (1:15). Leave empty to start at the beginning.
Optional. Same format as the start time. Leave empty to keep everything up to the end.
The converted file will be at or just under this size.
How to use this tool
- 1
Upload the MKV files
Drop up to 20 .mkv files of up to 95 MB each, or tap to choose them from your device.
- 2
Leave the codecs on H.264 and AAC
Those two are preset because every editor imports them. Use Advanced settings to cut a start and end time, scale to 1080p or 720p, or lower the Audio bitrate for a voice-only recording.
- 3
Press Convert to MP4
Download the MP4s one by one or as a ZIP. Uploads and results are removed automatically after 30 minutes.
Why so many recordings end up as MKV
Matroska started in 2002 as an open, royalty-free container built on EBML, a binary cousin of XML. It can hold any number of video, audio and subtitle tracks plus chapters and attachments such as fonts, which is why film rips, anime fansubs and archives use it.
The other big source is screen recording. OBS Studio has long recommended MKV for recordings because a crash, a full disk or a power cut still leaves a playable file. An MP4 interrupted mid-recording is usually unreadable, since its index is written only when recording stops. The trade-off arrives when you try to edit: iMovie, Final Cut Pro and QuickTime Player do not open MKV, and Premiere Pro's support for it is limited, so the file you were careful to protect will not import.
Converting fixes that in one pass. If you only need the video for a chat app with a size limit, convert first and then follow our guide to compressing video for Discord and email.
Which apps open MKV and which need MP4
| from ↓ · to → | VLC | QuickTime Player | iMovie | Final Cut Pro | iPhone Photos |
|---|---|---|---|---|---|
| MKV | MKV to VLC: yes | – MKV to QuickTime Player: no | – MKV to iMovie: no | – MKV to Final Cut Pro: no | – MKV to iPhone Photos: no |
| MP4 | MP4 to VLC: yes | MP4 to QuickTime Player: yes | MP4 to iMovie: yes | MP4 to Final Cut Pro: yes | MP4 to iPhone Photos: yes |
MKV
Matroska video
MKV is the Matroska multimedia container, an open-source format first released in 2002. It can hold nearly any video and audio codec plus unlimited audio tracks, subtitle tracks, chapters and attachments in one file. That flexibility makes it popular for films with several languages, screen recordings from OBS and long-term archiving. Phones, browsers, editors and some TVs do not support MKV, even when they support the codec inside.
- Compression
- Lossy or lossless
- Transparency
- –
- Animation
- –
- Introduced
- 2002 · Matroska project
MP4
MPEG-4 video
MP4 (MPEG-4 Part 14) is a multimedia container standardised by ISO/MPEG and based on Apple's QuickTime format. It usually holds H.264 or HEVC video with AAC audio, and can also carry subtitles, chapters and metadata. It is the most compatible video format in the world, playing on phones, browsers, TVs, game consoles and social platforms. The video inside is almost always lossy, so repeated re-encoding gradually reduces quality.
- Compression
- Lossy
- Transparency
- –
- Animation
- –
- Introduced
- 2001 · Moving Picture Experts Group (MPEG)
MKV is a flexible archive container that most editors and phones ignore; converting to MP4 trades the extra tracks for a file that imports and plays everywhere.
Getting a clean MP4 from an MKV
| Do | Don't |
|---|---|
| Keep Resolution on Same as source for game footage you will edit. | Rename .mkv to .mp4 and expect editors to accept it. |
| Lower Audio bitrate to 128 kbps for talks and meetings. | Delete the MKV if it carries extra languages or subtitles. |
| Use Start at and End at to drop dead air before converting. | Raise Frame rate above the source; frames are only duplicated. |
MKV files often contain codecs that MP4 can carry too, such as H.264 video and AAC audio from OBS. Others hold HEVC, VP9 or FLAC audio from rips. The converter normalizes all of these to H.264 and AAC because that is the combination iPhones, Android phones, Windows Media Player and smart TVs agree on. If your target is a Mac editing timeline rather than a phone, MKV to MOV produces the QuickTime container used across Apple's pro apps.
MKV to MP4 FAQ
Is this MKV to MP4 converter free?
Yes, with no watermark and no account. The limits are 20 files per batch and 95 MB per file, and there is no daily cap on batches.
Why won't iMovie or Final Cut Pro import my .mkv file?
Apple's editors and QuickTime Player never added Matroska support, so they grey the file out in the import dialog. Converting to MP4 with H.264 and AAC gives them a container and codecs they read natively.
What happens to subtitles and extra audio tracks?
MKV can hold many audio languages and subtitle formats such as ASS and PGS that MP4 does not support. The MP4 is meant for playing and editing, so keep the original MKV if you need every language or the styled subtitles.
Is converting MKV to MP4 lossless?
No, the video is re-encoded to H.264. At Quality (CRF) 23 the difference is hard to see; set it to 18 if you plan to edit and export again. A pure container swap, called remuxing, is what OBS's own Remux Recordings command does when the codecs already fit MP4.
My OBS recording is over 95 MB. What now?
Use OBS's File > Remux Recordings, which rewraps the file locally without re-encoding, or split the recording into shorter scenes. Files above 95 MB cannot be uploaded here.
Can I use the mkv to mp4 converter online on a phone?
Yes. The page works in Safari and Chrome on iOS and Android; pick the file from Files or your downloads folder, convert, and the MP4 saves back to the same place.