mechanical calculator
Gear & Pulley Ratio Calculator
Find the drive ratio, output speed, and torque multiplication for a gear or pulley pair.
How it works
ratio = driven / driver. Output speed = input x driver / driven. Torque multiplies by the ratio.
Worked example
20-tooth driver into 60-tooth driven at 1,800 rpm: ratio 3:1, output 600 rpm, torque x3.
When to use it
- Use tooth counts for gears or pitch diameters for pulleys - the ratio is identical.
- A reduction (ratio greater than 1) trades speed for torque.