Mac OS size?

[malizivko]

I have MacBook Pro (Retina, 13-inch, Mid 2014) with only 128gb, which OS version would take least space....

 

[Fishrrman]

The "space difference between" OS's such as El Capitan, Low Sierra, High Sierra really isn't that great.

I'll guess that El Cap may use "the least".
But it's getting a little older now.
Low Sierra (10.12) might be better.