More about belt pitch and pitch diameter

AutomationDirect currently offers belts (and pulleys) in MXL, XL, and L sizes, with corresponding pitches of 0.08, 0.200, and 0.375 as shown in these diagrams:

Pulleys sizes are based on number of teeth. A value for Pitch Diameter is typically supplied for convenience. The following diagram details the pitch diameter:

Please reference this PDF for more info on belt pitch and pitch diameter.