What is the Gear Ratio Calculator?
The gear ratio calculator is a free online tool that helps you work out gear ratio quickly and accurately. It uses the standard formula Ratio = driven / driving; output rpm = input x driving / driven and shows the result instantly as you type, along with a full breakdown so you can see exactly how the answer was reached.
How to use this calculator
- Enter teeth on the driving and driven gears.
- Optionally enter input rpm.
- See the gear ratio.
Formula used
Ratio = driven / driving; output rpm = input x driving / drivenExplanation of each input
- Driving gear teeth โ the driving gear teeth used in the calculation.
- Driven gear teeth โ the driven gear teeth used in the calculation.
- Input speed (rpm) โ the input speed used in the calculation.
Understanding your result
- Gear ratio โ the calculated gear ratio.
- Output speed โ the calculated output speed in rpm.
Step-by-step calculation
For the example values 12 and 36 teeth:
- Apply the formula:
Ratio = driven / driving; output rpm = input x driving / driven - Substitute the values: 36/12
- Result: 3:1, output 333 rpm
Worked example
| Inputs | 12 and 36 teeth |
|---|---|
| Working | 36/12 |
| Result | 3:1, output 333 rpm |
Benefits and practical uses
This calculator saves you time and reduces errors when you need gear ratio. It is useful for students, professionals and anyone who wants a fast, reliable answer without manual calculation. Results update instantly, work in your browser and can be copied or shared in one click.
Assumptions and limitations
- Ideal gear mesh, no losses.
Frequently asked questions
What does a 3:1 ratio mean?
The driving gear turns three times for each turn of the driven gear, trading speed for torque.
Disclaimer: Results are provided for general information. Please verify important figures independently.