Created By : Sunil Kumar Gandipadala

Reviewed By : Rajashekhar Valipishetty

Last Updated : Apr 10, 2023

Find the mechanical advantage a two-gear setup produces in a machine taking help of the Gear Ratio Calculator. Enter the inputs such as input, output teeth number in the respective input fields and click on the calculate button to evaluate the gear ratio.

Input gear teeth number
Output gear teeth number
Gear ratio
Mechanical advantage
Input rotational speed
Output rotational speed
Input torque
Output torque

What is a Gear?

Gear is a toothed wheel that can alter the torque, direction, speed and rotational movement applied to it, etc. Gears are available in different sizes and shapes and they denote the translation or transfer of rotational movement. If two or more gears meshed together in a system then transfer of movement happens and the system of gears are called gear train.

What is Gear Ratio and How to Calculate it?

Gear Ratio is the ratio of circumferences of input gear to the output gear in a gear train. Gear Ratio will evaluate the number of teeth each gear needs in order to produce desired angular velocity, torque or speed.

We can express the gear ratio using the formula Gear Ratio = (π * diameter of input gear)/(π * diameter of output gear)

Simplifying the equation obtained we get the equation as Gear Ratio = (diameter of input gear)/(diameter of output gear)

Gear Ratio = radius of input gear/radius of output gear

We can employ the same technique by considering the number of teeth. It is same as finding circumference of gears. We can write the gear's circumference by multiplying both sum of tooth's thickness and spacing between teeth and the number of teeth the gear has.

Gear Ratio = (input gear teeth number * (gear thickness + teeth spacing)) / (output gear teeth number * (gear thickness + teeth spacing))


Thickness and Gear Train's Spacing needs to be same in order to engage the gears smoothly. Canceling the Gear Thickness and Teeth Spacing we will have the equation as follows

Gear Ratio = input gear teeth number / output gear teeth number

Just like any other ratios we can express the gear ratio in the form of a decimal, fraction, ordered pair of numbers separated by colon, etc. If we take the reciprocal of gear ratio in its fractional form then we get the mechanical advantage of gear train or gear system.

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FAQs on Gear Ratio Calculator

1. What is the Gear Ratio Formula?

Gear Ratio Formula = radius of input gear/ radius of output gear.

2. What does gear ratio mean?

Gear Ratio means the ratio obtained on dividing the input gear teeth number with output gear teeth number.

3. Does gear ratio affect horsepower?

On changing gear ratio horsepower will not vary. RPM and Torque will change when gear ratio is varied but not horsepower.