Belt Drive Ratio & Length
Calculate the speed ratio, driven speed, belt length, wrap angle and belt speed of a two-pulley belt drive, free online.
About this calculator
Speed ratio = driven diameter รท driver diameter; driven rpm = driver rpm รท ratio. Open-belt length L โ 2C + ฯ(D + d)/2 + (D โ d)ยฒ รท 4C. Wrap angle on the small pulley = 180ยฐ โ 2ยทasin((D โ d) รท 2C); keep it above about 120ยฐ. Belt speed v = ฯยทdยทn.