How to determine scene scale with using ZBrush and Keyshot

[jlgroff]

I understand that the unit settings for scene scale (or whatever it's called) is important to get correct or more numerically reasonable lighting in Keyshot. I haven't found an easy way to figure out the true scale of objects I bring in from Zbrush - I basically just use guess work based on the size of the "brush". I don't do product renders where this is more important but I do find it sometimes problematic to pick the right units - cm, mm, meters - etc. I usually just settle on inches and deal with weird number. Any suggestions?