How do I compress MKV files?

Run "npx optimo video.mkv" to compress MKV with lossless optimization. For stronger compression, add --lossy. For size reduction through resizing, add --resize followed by a percentage, dimensions, or target file size.

What is the best way to reduce MKV file size?

The two biggest levers are resizing (reducing dimensions to match display size) and lossy compression. Resizing usually has a larger impact than codec-level compression. Sometimes converting to a more efficient format is the best approach.

Compress MKV files

MKV is a flexible container, but it’s not a standard delivery format. Compression usually means converting to MP4/WebM for predictable playback.

Last updated: 2026-03-18

To compress MKV files, run npx optimo video.mkv. Optimo applies FFmpeg-powered compression by default. For stronger reduction, use --lossy or --resize to shrink dimensions — often the single biggest lever for file size.

Start with optimo

First, run optimo on your video file:

npx optimo video.mkv

This is safe: optimo keeps the original if the output isn't smaller.

Two big levers

1) Lossy mode

npx optimo video.mkv --lossy

2) Resize (dimensions)

npx optimo video.mkv --resize w1280

Practical tips

Convert to MP4 when you want broad compatibility.
For modern browsers, WebM can be a strong alternative.
If the file is huge, resize first; it’s the fastest win.

Optimize MKV Resize MKV MKV format guide

Consider converting

Sometimes the best compression is picking a better delivery format.

MKV → MP4 MKV → WebM MKV → MOV MKV → AVI MKV → OGV

Popular conversions

Convert MKV to MP4 Convert MKV to WebM Convert WebM to MKV Convert MP4 to MKV Convert MOV to MKV Convert MKV to MOV Convert MKV to AVI Convert AVI to MKV

Frequently asked questions

How do I compress MKV files?: Run "npx optimo video.mkv" to compress MKV with lossless optimization. For stronger compression, add --lossy. For size reduction through resizing, add --resize followed by a percentage, dimensions, or target file size.
What is the best way to reduce MKV file size?: The two biggest levers are resizing (reducing dimensions to match display size) and lossy compression. Resizing usually has a larger impact than codec-level compression. Sometimes converting to a more efficient format is the best approach.