Belt Length Formula
L = (2C + (1.57*(D + d))) + ((D - d)^2)/4C)
Where:
L = Belt Length Non clutched add .5 to 1 inch for most clutched applications
C = Length Center to Center shafts
D = Diameter of Large Sheave
d = Diameter of Small Sheave
Diameter of the Sheave means the outer most diameter of a new belt in the Sheave