Muxing out subs & audio tracks increases file sizes?

[Flyentologist]

I’ve recently started nearing my storage limits and before buying new drives I thought it prudent to take proactive action and go through all my media and mux out audio and subtitle tracks I have no need for. However in almost every single case, stripping foreign subtitles, audio tracks, and commentaries tend to increase file sizes by between 500MB-2GB when using MakeMKV.

My main question is, why? Is there a lot of decompression happening? Even just rewriting the media file with no changes at all leads to larger files.

[Woodstock]

There is no need to use MakeMKV to just remove tracks from your existing MKV files; mkvmerge from mkvtoolnix can do it.

However, just removing audio and subtitle tracks is not going to make much of a dent in your file sizes, as they're rarely more than a percent or two of the overall size. Using a tool like handbrake to compress the video better will make a HUGE difference... And it can leave out tracks you don't want.