How do I crop by values?

[Steve_k2400]

(Today, 07:09 AM)Ofnuts Wrote: Have you looked into defining a tool preset for this?

No, at the end I used Krita for the images.
It was a bunch of huge repetitive textures in which zooming out and in to set the crop precisely was just too tedious in Gimp.
Zooming at the desired area and then playing with the numeric height/width values and then hitting the crop button was simpler.
It's done now and I learned a lot about Gimp as well so many thanks for all of your help!