RC Gear Ratio Calculator
Compare setups side by side to find the ideal pinion/spur combination — with final drive ratio (FDR) and rollout for every change.
Free · iOS & Android
Get this Calculator on your Phone
Pit Calc Pro lets you calculate gear ratios, suspension geometry, corner weights, oil viscosity, and more!
Current
New
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 |
Change
0.0%
No change
Current
Gear Ratio
4.00:1
New
Gear Ratio
4.00:1
Free to start · iOS & Android
Setup App & Race Log
Save your gearing and the rest of your setup, get AI tuning answers, and log your races.
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.
- • Want the actual mph? The RC speed calculator turns your gearing, motor Kv, and voltage into a top-speed number.
- • Your settings are automatically saved for your next visit.
Ask your AI RC mechanic
Get answers about setups and gearing in seconds, always handy.
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