@unknownuser said:

This Bounding Box includes rotation, so X, Y , Z sizes are not object sizes.

Is there a way to get exact sizes of objects (or groups,entities.. any kind of selection)according to local ("objects") or world coordinate system? (Sorry if my terminology is wrong).

Here is my solution:

b = instance.definition.bounds t = instance.transformation x = ((b.max.x-b.min.x) * t.xscale) y = ((b.max.y-b.min.y) * t.yscale) z = ((b.max.z-b.min.z) * t.zscale)

Hope it helps
Have fun!