kV (Motor Velocity Constant)

kV is a motor specification that describes how fast a motor will spin for each volt applied with no load attached. It is typically expressed in RPM per Volt (RPM/V).

A motor with a higher kV will spin faster for a given voltage but generally produce less torque per ampere. A motor with a lower kV will spin slower but typically produce more torque per ampere.

kV is determined by the motor’s design and winding configuration and cannot be changed through software settings. It can usually be found in your motor datasheet.

⚠️ kV is not the same as kilovolts (kV), a unit of electrical voltage. In the context of electric motors, kV refers to the motor velocity constant.

Example

A motor rated at 100 kV supplied with 50V will have a theoretical no-load speed of:

100 × 50 = 5000 RPM

In practice, the actual motor speed will be lower due to load, losses, and controller limitations.

In simple terms: kV tells you how many RPM a motor will spin for every volt applied.