CR calculation, deck height/effective dome volume?

I don't like the online calculators because 99.9999999% of everything built is zero deck, or negative deck volume.

I just do the math. I think about it like a Chevy. A domed piston on a Chevy, with a zero deck doing the downfill method will actually calculate the dome minus valve notches. If it has a positive deck, you have to account for the actual diameter of the piston that is out of the deck, however far that is.