RPM / gear ratio / wheel circumference to top speed calculator

This form allows you to calculate how fast your car will go if your motor turns at a certain speed through a gearbox. It's primary purpose is for electric vehicle enthusiasts to work out what maximum RPM limit they should look for in a motor. Obviously this depends on your torque versus your friction losses, which we make no attempt to calculate here.

The Torque and Vehicle Weight fields are optional. If supplied they will allow the calculation of the Force and Acceleration / 0-100km/hr outputs.

Gear ratio[1] :
[2]. centimetres


[1] Gear ratios in gearbox range from 5:1 to 0.7:1. For motorcycles, put in the rear gear teeth and front gear teeth (i.e. rear:front).

[2] Car tyres are around 160-190cm, see this calculator).

[3] This assumes perfect traction and full power from start. The ability to deliver this may vary from the ideal.