Motor Kv ↔ Kt Converter (RPM/V ↔ Nm/A)

Battery animation
Enter motor Kv (RPM per volt). Leave empty if using Kt.
Enter torque constant (Nm per amp). Leave empty if using Kv.
Used to compute no-load speed (Kv × V) if provided.
Used to compute motor torque = Kt × I.
Example: 4 = motor turns 4× per 1 wheel rotation. Default 1 (hub motor).
Use meters (e.g., 0.35 m). Used to compute wheel torque and linear speed.
Multiply wheel torque by this to account for gearbox losses. Default 0.95.

Motor Kv tells how many RPM the motor produces per volt under no-load, while Kt represents torque produced per ampere. This converter instantly calculates either constant and optionally computes torque, RPM, wheel torque and vehicle speed based on user inputs.

Kv vs Kt — What's the difference?

Kv (RPM/V) describes speed-per-volt while Kt (Nm/A) describes torque-per-amp. Together they define motor performance, and they are mathematically related for BLDC machines.

Formula: Kt ≈ 60 / (2π × Kv)

Where motor Kv/Kt conversion is useful

  • eBike motors / controllers
  • Electric scooter motors
  • RC brushless motors
  • DIY EV projects
  • BLDC motor design

Optional advanced calculations

  • No-load RPM = Kv × V
  • Motor torque = Kt × I
  • Wheel torque (with gear losses)
  • Linear speed based on wheel radius

Frequently Asked Questions

Q: Are Kv and Kt always mathematically linked?
Yes for brushless motors. Higher Kv means lower Kt and vice-versa.
Q: Does higher Kv mean more speed?
Higher Kv results in higher RPM per volt, so motors spin faster at the same voltage.
Q: Does Kt directly represent motor torque?
Yes. Torque output equals Kt × current assuming ideal efficiency.
Q: What if I only know Kv?
You can compute Kt using the conversion formula and vice-versa.
Q: Why optional voltage and current?
Voltage lets us compute no-load RPM while current lets us compute torque output.