We can form the following definitions and equations:
N = Number of teeth on pulley.
P = Pitch of Belt (distance between teeth).
Cb = Circumference of belt.
Db = Diameter of belt.
Dpo = Outer Diameter of pulley.
Dpi = Inner Diameter of pulley.
Tb = Thickness of belt, measured from tooth valley to the flat side of the belt.
Ht = Height of the tooth on the belt.
Equations:
Cb=N⋅P
Db=Cbπ
Dpo=Db−2⋅Tb
Dpi=Dpo−2⋅Ht