Gear Ratio Calculator

Your details

Forward computes the ratio from teeth. Reverse finds the driven teeth needed for a target ratio.
The input (driving) gear connected to the power source.
teeth
The output (driven) gear that the driver turns.
teeth
Rotational speed of the driver gear, in revolutions per minute.
rpm
Torque supplied at the driver gear. Leave blank to skip the torque output.
N·m
Power kept per gear mesh. Spur gears are about 96-99%; worm drives much lower.
%
Overall gear ratioReduction (torque gain)
3

Driven teeth ÷ driver teeth, multiplied across stages.

Ratio as N:1 / reduced3.000:1 (3:1)
Output speed500rpm
Output torque29.1N·m
Torque multiplier3×
Overall efficiency97%
Output rpm500
Output torque (N·m)29.1

The output spins at 500 rpm at a 3.00:1 ratio.

  • A ratio of 3.000:1 means the output gear makes 0.333 turns for every full turn of the driver.
  • This is a reduction drive: the output turns slower but with more torque.
  • At 97.0% efficiency the output delivers 29.10 N·m from 10 N·m in.

Next stepFor longer gear trains, multiply each stage ratio together; idler gears change direction only, not the ratio.

 = Powered by OnlyCalculators