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!
Change
0.0%
No change
- CurrentNew
- Gear Ratio
- 4.00:1
- 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 |
Free to start · iOS & Android
RC Setup App
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.
RC Deal Alerts
Get notified when the RC stuff you want goes on sale
More RC Calculators
Free RC tools to dial in your car between rounds.
Drivetrain
RC Speed Calculator
Motor Kv, battery voltage, gearing, and tire size → top speed of any electric RC car.
RC Pinion Recommender
What pinion should I run? Pick your car and motor; get a starting pinion from real race setups, with the range racers run.
RC Gear Ratio Chart Maker
Build a printable pinion/spur chart for any class: gear ratio (FDR) or rollout (mm). 1/10, 1/12 pan, 1/8 presets included.
RC Crawl Ratio Calculator
Total motor-to-wheel reduction for crawlers and trail trucks: pinion, spur, transmission, axle and portal gears.
RC Battery Runtime Calculator
How long will your LiPo last? Estimate runtime by class and driving style.
Shocks
Chassis & Suspension
RC Corner Weight Calculator
Enter per-wheel weights to compute cross weight and balance, critical for oval and on-road tuning.
RC Pill Insert Calculator
Suspension pill inserts: see how a position change moves arm sweep, kick-up, anti-squat and track width. 232+ models.
Mini-Z Wheel Offset Calculator
Fitting an AutoScale body to a Kyosho Mini-Z? Get the exact wheel offset for any width, plus a wheelbase & motor-mount reference.