Cars & Vehicles
Gear ratio calculator
Drive and driven gear teeth → gear ratio.
- Instant
- Free
- Private (processed locally)
- No sign-up
Calculate a gear ratio
Enter the drive gear teeth and the driven gear teeth. The tool gives the ratio as “X : 1”.
Understanding the ratio
- Ratio = driven ÷ drive
- > 1: reduction (more torque)
- < 1: overdrive (more speed)
- Stages in series: multiply the ratios
Example
| Input | Value |
|---|---|
| Drive gear | 13 teeth |
| Driven gear | 41 teeth |
| Ratio | ≈ 3.15 : 1 |
100% local calculation, no data sent.
Frequently asked questions
How is the ratio calculated?
Ratio = driven gear teeth ÷ drive gear teeth. E.g. 41 ÷ 13 ≈ 3.15 : 1.
What does a ratio > 1 mean?
A reduction: the output spins slower but with more torque. Typical of a rear axle.
And a ratio < 1?
An overdrive: the output spins faster, less torque. Useful at high speed to lower the engine RPM.
How do I combine several stages?
Multiply the ratios: total ratio = gearbox ratio × final drive ratio, for example.