0.030” imperial = 0.762mm, 0.8mm for a realistic measurement.
in this instance you want to have a rough clearance between underside of string/nut slot and top of first fret of roughly 0.8 mm. (Correct me if I’m wrong on that statement McCreed)
That's right FW.

Fret height (X) + .030" = (Y) string slot bottom

Fine tune from there.