Gear Ratio Calculator
Calculate the gear ratio, output speed, torque, and other parameters for a simple two-gear system. Input the number of teeth on the driving and driven gears, and optionally the input RPM and torque.
Published by:
isCalculator Editorial Team
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How to Use the Gear Ratio Calculator
This calculator computes the gear ratio between two gears and, optionally, the resulting output RPM and torque. All inputs use metric units (teeth count, RPM, Nm).
- Enter Driving Gear Teeth – The number of teeth on the gear that provides the input motion (must be a positive integer).
- Enter Driven Gear Teeth – The number of teeth on the gear that receives the motion (must be a positive integer).
- (Optional) Enter Input RPM – The rotational speed of the driving gear in revolutions per minute (non-negative number).
- (Optional) Enter Input Torque – The torque applied to the driving gear in Newton-meters (non-negative number).
- Click "Calculate" – The results will display the gear ratio, and if provided, the output RPM and output torque.
Key Formula: Gear Ratio = Driven Teeth ÷ Driving Teeth. Output RPM = Input RPM ÷ Ratio. Output Torque = Input Torque × Ratio.
All inputs must be positive integers for teeth, and non-negative numbers for RPM and torque. Errors are highlighted in red.
Previous Results
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Frequently Asked Questions
A gear ratio is the ratio of the number of teeth on the driven gear to the number of teeth on the driving gear. It determines the speed and torque conversion between gears.
Output RPM = Input RPM / Gear Ratio. For example, if input RPM is 1000 and gear ratio is 2, output RPM is 500.
Torque is inversely related to speed. Output Torque = Input Torque × Gear Ratio. A higher gear ratio increases torque but decreases speed.