Compress MKV Video Online
MKV (Matroska) is a flexible container often used for high-quality rips with multiple audio/subtitle tracks, which makes files large.
Drag and drop your video here
or
Choose videoMP4, MOV, AVI, MKV, WebM and more · up to 500MB per file · select several to batch compress
obs-recording.mkv
Ready to download
64 MB
from 420 MB
Consolidates multi-track MKV files into a single, lightweight MP4 stream
Removes the overhead of unused audio/subtitle tracks you don't need
Produces a file that's playable in apps and platforms that don't support MKV natively
Why compress MKV files?
Compressing to MP4 strips down to a single video/audio track and re-encodes efficiently, drastically shrinking file size.
Recommended settings
What we'd pick for this job. After choosing a file, resolution sits right under the compression settings, crop is under “Resize / crop”, and codec is under “Advanced settings”.
By quality · Strong
Screen recordings compress hard without visible loss.
H.264
MP4 output plays where MKV often won't.
1080p for 1440p / 4K screen captures
Text stays readable at 1080p while the file shrinks a lot.
Original
Keep the full recording area.
The raw recording
Burn in subtitles first if you need them.
Tips for the best result
Great for screen recordings
Recording software like OBS commonly saves MKV at high bitrates. Screen content has large static areas, so it compresses exceptionally well — often by 80% or more.
MP4 output plays everywhere
Many phones, browsers, and social platforms won't play MKV. The compressed file is an MP4, so it's ready to upload or share without a separate conversion step.
Extra tracks are dropped
MKVs can carry several audio and subtitle tracks. The output keeps the main audio track only, so burn in subtitles beforehand if you need them.
Start from the original file
Compression is lossy, so re-compressing a video that has already been shrunk (or sent through a chat app) stacks artifacts. Always work from the camera or editor export.
How it works
Step 1
Upload
Drop your file in — up to 500MB free.
Step 2
Pick a quality
Basic, Strong, or Superb compression.
Step 3
Download
Get your smaller video in seconds.
Frequently Asked Questions
MKV files often bundle multiple audio tracks (different languages), subtitle tracks, and chapter data alongside a high-bitrate video stream — all of that adds up in file size.
Yes, the compressor keeps one video and one audio track and outputs a standard MP4 — if you need a specific language track, make sure it's the default track in your source file.
Not natively in most cases — MKV support is inconsistent across devices and browsers, which is a common reason to compress and convert it to MP4.
It can, since MKV sources are often high-bitrate or 4K rips — larger source files simply take more processing time regardless of format.
'Basic' preserves the most detail for archival-quality sources; 'Strong' or 'Superb' are better if your goal is just a smaller file to share or stream elsewhere.