Gear Ratio Calculator

Inputs

View results
Teeth on the driving (input) gear — e.g. the pinion or front sprocket.
Teeth on the driven (output) gear — e.g. the ring gear or rear sprocket.
Speed of the driving gear / engine.
rpm
Torque at the driving gear (optional).
N·m
Drive-wheel diameter, for road speed (optional). 0 to ignore.
mm

Results

Default result
Edit inputs
Gear ratio(i)
3
Pass

3.00:1 — reduction (torque up, speed down).

driven ÷ driving (n:1).

Also computed

Output speed(n₂)1,000rpm

Output torque(T₂)300N·m

Ideal, before losses.

Vehicle speed119.3km/h

At the output speed, from tire diameter.

Method notes 3 notes
  • Ratio i = driven teeth ÷ driving teeth. Output speed = input ÷ i; output torque = input × i.
  • Torque is ideal (100% efficient); real gear trains lose a few percent per mesh.
  • Vehicle speed assumes the driven gear turns the wheel directly — for a full drivetrain, multiply the transmission and final-drive ratios first.

Powered by MachineCalcs ↗