RPM Calculator
Convert RPM, and calculate pulley, gear, and wheel speeds
Frequently Asked Questions
Angular velocity (rad/s) = RPM ÷ 60 × 2π. Each revolution sweeps 2π radians, so dividing RPM by 60 gives revolutions per second, then multiplying by 2π converts to radians per second.
Driven RPM = driver RPM × (driver pulley diameter ÷ driven pulley diameter), reduced slightly for belt slip (typically 1-3% for V-belts, near 0 for toothed belts).
Output RPM = input RPM ÷ gear ratio, where gear ratio = driven gear teeth ÷ driver gear teeth. A ratio above 1 is a speed reduction; below 1 is a speed increase.
Wheel RPM = (speed ÷ tire circumference) × 60. Engine RPM is then wheel RPM × the overall transmission and final-drive ratio.