Work out sprocket ratio instantly with clear inputs, formula shown and shareable results.
Chain drives are positive, so the tooth ratio sets the speed ratio exactly: output speed is input speed divided by N2/N1. Chain linear speed is teeth times pitch times rpm divided by 12, and it is the figure that governs lubrication method and permissible power.
Speed and torque
Output rpm = input rpm x N1 / N2; torque multiplier = N2 / N1
Chain speed
V fpm = N1 x pitch in x rpm / 12
Output rpm = input rpm x N1 / N2; torque multiplier = N2 / N1. Chain drives are positive, so the tooth ratio sets the speed ratio exactly: output speed is input speed divided by N2/N1.
Fewer teeth means a larger articulation angle at each joint, which raises impact and wear sharply. Seventeen teeth is the usual practical floor for a power drive.
This calculator takes 4 inputs: Driving sprocket teeth, Driven sprocket teeth, Input speed, Chain pitch. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.