Gear Ratio Calculator

Find gear ratio and output speed.

Gear ratio (:1) 2

Output speed (RPM) 500

Formula: ratio = driven ÷ driver

Step-by-step with your numbers:

1. Values used:

2. Driven gear teeth = 40

3. Driver gear teeth = 20

4. Input speed = 1,000 RPM

6. Gear ratio = Driven gear teeth / Driver gear teeth = 40 / 20 = 2:1

7. Output speed = 500RPM

Did we solve your problem today?

Gear ratio sets the trade-off between speed and torque.

The math behind it

ratio = driven teeth ÷ driver teeth; output RPM = input RPM ÷ ratio. A ratio above 1 reduces speed and multiplies torque.

40/20 = 2:1 → 1000 RPM in, 500 RPM out.

Torque?

Output torque = input torque × ratio (ignoring losses).