What is gear mechanical advantage?

Gear mechanical advantage (MA) is the ratio of the driven (output) gear tooth count to the driver (input) gear tooth count. It tells you how much the gear pair multiplies torque. MA = Driven Teeth / Driver Teeth = Output Torque / Input Torque.

What is the difference between gear ratio and mechanical advantage?

They are the same number for a simple two-gear pair. Gear ratio = Driven / Driver. Mechanical advantage = Output Force (or Torque) / Input Force (or Torque). For a single stage they are equal. In multi-stage gear trains the overall MA is the product of all stage ratios.

Does a higher MA mean more torque or more speed?

A higher MA (greater than 1) means more output torque but less output speed — a torque multiplier / speed reducer. An MA less than 1 means more output speed but less torque — a speed multiplier / torque reducer.

How does tooth count determine MA?

Each tooth on a gear represents one "step" of motion. A driven gear with 40 teeth rotates once for every two rotations of a 20-tooth driver, so MA = 40/20 = 2. Torque doubles while RPM halves, conserving power (ignoring friction).

What about efficiency and friction losses?

This calculator assumes 100% efficiency (ideal gears). Real spur gears are typically 97–99% efficient per mesh. Multiply the ideal output torque by the efficiency factor (e.g. 0.98) to estimate real-world output.

Can I use this for more than two gears?

This tool covers a single driver–driven pair. For a multi-stage gear train, calculate each stage separately and multiply the individual gear ratios together to get the overall ratio and MA.

Gear Mechanical Advantage Calculator

Name: Gear Mechanical Advantage Calculator
Availability: InStock
Author: Nham Vu

Enter driver and driven gear tooth counts plus an input torque or speed to calculate mechanical advantage, gear ratio, output torque, and output speed.

Gear Inputs

Driver Teeth (input gear)

Driven Teeth (output gear)

Optional — enter input values to calculate outputs.

Input Torque

N·m

Input Speed

RPM

Gear Pair Diagram

Enter gear tooth counts above and click Calculate.

Summary

Enter driver and driven gear tooth counts plus an input torque or speed to calculate mechanical advantage, gear ratio, output torque, and output speed.

How it works

Enter the number of teeth on the driver (input) gear.
Enter the number of teeth on the driven (output) gear.
Optionally enter input torque (N·m) to calculate output torque.
Optionally enter input speed (RPM) to calculate output speed.
The calculator applies MA = Driven Teeth / Driver Teeth.
Results display gear ratio, mechanical advantage, output torque, and output RPM.

Use cases

Size gears for a motor-driven machine that needs more torque at lower speed.
Verify gear train designs for robotics, bicycles, or automotive transmissions.
Calculate the output torque of a reduction gear for a servo or stepper motor.
Determine how much a speed-increasing gear stage reduces available torque.
Solve physics homework problems on gear trains and mechanical advantage.
Compare multiple gear ratio options side by side before building a prototype.
Estimate output RPM of a gear-reduced DC motor for conveyor or winch design.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu