Image Scaling Measurements
I use GIMP 2.10 in Linux Mint 19.
I noticed the other day, when needing to check the size of an image in millimetres - to check max print size - that clicking on the millimetre or centimetre option does not correctly convert the size of the image from px to mm or cm. It is, in fact, very incorrect.
The file I was working with converted 3648px x 2736px to 6.08mm x 4.56mm. Correct millimetre measurement should be 965.2mm x 723.9mm