Gear Ratio Calculator

What Is Gear Ratio?

Gear ratio compares the number of teeth on the driven (output) gear to the driver (input) gear. It determines how speed and torque change through a gear train. A ratio greater than 1 reduces speed but multiplies torque.

Gear Ratio Formulas

GR = N_driven / N_driver

Output speed: RPM_out = RPM_in / GR

Output torque: T_out = T_in × GR

Example: a 20-tooth driver and 40-tooth driven gear give GR = 2. At 3000 input RPM, output speed is 1500 RPM. Input torque of 200 N·m becomes 400 N·m at the output.

Frequently Asked Questions

Which gear is the driver?

The driver (input) gear receives power from the motor or crankshaft. The driven (output) gear is connected to the load or wheels.

Does a higher gear ratio mean faster or slower output?

A higher gear ratio slows the output shaft (RPM_out = RPM_in / GR) but increases output torque.

Can I calculate gear ratio from RPM values?

Yes. GR = RPM_in / RPM_out. Use the Gear Ratio RPM Calculator for speed-focused calculations.

What is mechanical advantage?

A gear ratio of 2 provides 2× torque multiplication at the cost of halving rotational speed, conserving energy (ignoring friction).

Do spur, helical, and bevel gears use the same formula?

Yes. Gear ratio is always the ratio of driven teeth to driver teeth, regardless of gear type.

Report

What Is Gear Ratio?

Gear Ratio Formulas

Related Tools

Frequently Asked Questions

Related Tools

Recent Visits

Finance Calc Kit