Compression height is the distance from the center of the wristpin to the top of the piston, not including domes.  So how do you properly calculate it?  Here's how:

By definition, compression height is the distance from the center of the wristpin to the top of the piston, not including domes. This distance needs to change depending on the engine's stroke, rod length, and block deck height. Here's the formula to find out what compression height you need.
(1/2 stroke + rod length + desired piston-deck clearance) - block deck height = required piston compression height.
Here's an example for a small Chevy with a 3.5-inch stroke, 5.850-inch rods,
a desired deck clearance of 0.005 inch, and a deck height of 9.00.
(1.75 + 5.850 + 0.005) - 9.00 = 1.395