⚙️ Gear Ratio Calculator
Work out the gear ratio between a driver and driven gear, and see how it affects output speed and torque.
What this calculator does
Gear ratio describes how the rotational speed and torque change between two meshed gears. This calculator uses the number of teeth on the driver (input) gear and the driven (output) gear to find the ratio, the resulting output speed, and the torque multiplication.
The formula
Gear ratio is calculated as Ratio = Driven Teeth / Driver Teeth. A ratio greater than 1 means the output gear turns slower than the input gear but with more torque, while a ratio less than 1 means the output spins faster but with less torque. Output speed is found with Output RPM = Input RPM × (Driver Teeth / Driven Teeth), and torque increases by the same factor the speed decreases, since gears conserve mechanical power (minus friction losses).
This calculator assumes an ideal gear mesh with no friction or slippage. Real mechanical systems will have some efficiency loss, so actual output torque will be slightly lower than the ideal calculation.