Pin Size:
Height: 1.25" inches  x  Width: 1.25" Inches
My Pin Grading system:
A Grade: A nearly perfect pin, with only up to 1 minor flaw.
B Grade: A Pin with 2-3 minor flaws
C Grade: A pin with about 4-6 minor or 1-2 major flaws.

(I would only go for C-Grade if you don't mind imperfections on your pins.)