RC Speed Calculator
A free RC car speed calculator — find the top speed of any electric RC car from motor Kv, battery voltage, gearing, and tire size.
Free · iOS & Android
Get this Calculator on your Phone
Pit Calc Pro lets you calculate top speed, gear ratios, corner weights, oil viscosity, and more!
Top Speed
Enter motor Kv, voltage, and tire diameter to calculate speed
- Gear Ratio
- 4.00:1
- Final Drive
- 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.
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