Or Bee See's method (copied from a different topic):
Quote:
Perforations represent the number of COMPLETE perforations per 20mm (2cm), so I take the longest measurement possible on each side of the stamp that covers complete perforations. Say I measure along 18 full holes and it is 26mm. So I use the formula: X holes/20mm = 18 holes/26mm. Do the math and it is 20 X 18 / 26 = 13.85 and you have an exact perforation. Scott would round that down to 13.75 or 13-3/4.
Posted 01/31/2012 10:34 am
