There are razors with 1/16 inch from the factory measurements..... Dubl Duck just for one, has 4/8, 9/16, 5/8, 11/16, 6/8, 7/8 that I have seen marked on their boxes they might even have more out there... C-MON is another that I have seen the 11/16 size marked....
We are talking about a fairly un-standardized system out there in the past so the top to bottom measurement is still probably still the most useful one.....

How ever you go ahead and measure how ya want.....