Top speed calculator
Enter your motor, battery and gearing to get the theoretical, unloaded top speed. Change one value at a time to see what a pinion swap or extra cell does.
Result
Enter positive values for every field.
Unloaded nominal estimate. Assumes no load, 100% efficiency, nominal voltage and no tire growth. Real-world speed is typically lower; this is not a measured result.
How it's calculated
Motor rpm = KV × (cells × volts per cell). Wheel rpm = motor rpm ÷ final drive ratio, where final drive = (spur ÷ pinion) × internal reduction. Speed = wheel rpm × tire circumference.
Theoretical vs real world
Real cars are slower: motors lose rpm under load, voltage sags, drivetrains and tires waste energy, and air resistance grows quickly with speed. Tire balloon can push the other way at high rpm. Use this number to compare setups and check gearing is sensible — not as a measured result. Measured results live in The Lab.
Check motor temperature after gearing up; taller gearing raises load and heat.