RC Gear Ratio Calculator
Compare setups side by side and find the ideal pinion/spur combination.
Current Setup
New Setup
Current
Gear Ratio
4.00:1
Change
0.0%
No change
New
Gear Ratio
4.00:1
Change Impact Chart
% change vs. your current setup. Click any cell to set it as the new setup.
| Spur ↓ Pinion → | 16T | 17T | 18T | 19T | 20T | 21T | 22T | 23T | 24T |
|---|---|---|---|---|---|---|---|---|---|
| 76T | |||||||||
| 77T | |||||||||
| 78T | |||||||||
| 79T | |||||||||
| 80T | |||||||||
| 81T | |||||||||
| 82T | |||||||||
| 83T | |||||||||
| 84T |
More acceleration (higher ratio)Higher top speed (lower ratio)Selected new setupCurrent setup
How to use this calculator
- • Enter your current pinion and spur tooth counts to establish a baseline.
- • Enter a new setup to compare, or click any cell in the chart to set it as the new setup.
- • Search for your car model to auto-fill the internal ratio.
- • Add rear tire diameter to calculate rollout — the distance traveled per motor revolution.
- • Positive change = higher ratio = more torque and acceleration.
- • Negative change = lower ratio = higher top speed, but more strain on the motor.
- • Your settings are automatically saved for your next visit.
Free app
Pit Calc Pro
Have this calculator handy at the track
Pit Calc Pro puts this gear calculator — and 6 more tools — right on your phone, so you're never without it when you need it most.
- Speed calculator
- Pill insert geometry
- Corner weights
- Shock oil viscosity
- Fuel usage
- Oil blending
