RC Top Speed Calculator
Calculate your RC car's theoretical top speed from motor KV, battery voltage, gear ratio, and tire diameter.
Free App
Pit Calc Pro
Have this calculator — and more racing calculators — right on your phone at the track.
Enter motor KV, voltage, and tire diameter to calculate speed
Gear ratio: 4.00:1 · FDR: 4.00:1
How to use this calculator
- • Enter your pinion and spur tooth counts to establish your gear ratio.
- • Search for your car to auto-fill the internal ratio and calculate the full final drive ratio (FDR).
- • Enter your motor's KV rating — found on the motor label or spec sheet.
- • Select your battery voltage from the quick-select chips, or type it in manually for LiHV or other chemistries.
- • Measure your rear tire outer diameter in millimeters and enter it above.
- • The speed grid shows how swapping pinion or spur gears changes top speed at your current KV, voltage, and tire size.
- • Click any cell in the grid to update your pinion and spur selection instantly.
- • Results are theoretical maximum speeds assuming 100% motor efficiency and no drivetrain losses.
- • 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 top speed calculator — and 6 more tools — right on your phone, so you're never without it when you need it most.
- Top speed calculator
- Gear ratio & FDR
- Pill insert geometry
- Corner weights
- Shock oil viscosity
- Fuel usage
