Divide selection using guides

[Ofnuts]

(04-14-2023, 09:33 AM)goran Wrote: I could use measure tool, but this won't work without calculator.

Well maybe yes... In the input fields where Gimp expects a number, you can enter expressions. For instance, to scale a 4000px image to half, instead of computing 2000 on the side, you just enter 4000/2 in the size field (and since it already contains 4000, you just add /2).