Free Tool by Machine Point Pulley & Belt Calculator Pulley & Belt Calculator Mode 1) Motor Pulley Size 2) Machine RPM 3) Belt & Center Distance Units mm in Decimals 0 1 2 3 Motor RPM Desired Machine RPM Machine Pulley Diameter (mm) Calculate Motor Pulley Formula: Dā = (Nā/Nā)ĆDā Motor RPM Motor Pulley Diameter (mm) Machine Pulley Diameter (mm) Calculate Machine RPM Formula: Nā = NāĆ(Dā/Dā) Motor Pulley Diameter (mm) Machine Pulley Diameter (mm) Center Distance C (mm) Belt Length from C Belt Length L (mm) Center C from L L ā 2C + (Ļ/2)(Dā+Dā) + (DāāDā)²/(4C)