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Gear Ratio Calculator

Find the gear ratio and output speed from two gears' tooth counts.

Inputs

Saved Scenarios

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Gear Ratio

3.00

Output Speed (RPM)

333.3

Spark says

How it's calculated

Formula

Ratio=Driven TeethDrive TeethOutput Speed=Input SpeedRatioRatio = \dfrac{Driven\ Teeth}{Drive\ Teeth} \quad\quad Output\ Speed = \dfrac{Input\ Speed}{Ratio}
Driven, Drive
— Tooth counts of the two gears

What is the Gear Ratio Calculator?

Gear ratio compares the tooth counts of two meshed gears, determining how speed and torque trade off between the input (drive) and output (driven) gear.

How to use it

  1. 1 Enter the number of teeth on the drive gear.
  2. 2 Enter the number of teeth on the driven gear.
  3. 3 Enter the input rotational speed.

Worked examples

20-tooth drive, 60-tooth driven, 1000 RPM in

3:1 ratio, output speed is 333.3 RPM.

Try it

Frequently asked questions

Does a higher gear ratio mean more speed or more torque?

A ratio above 1:1 (more teeth on the driven gear) reduces output speed but increases torque — useful for climbing or heavy loads. Below 1:1 does the opposite.