DC Motor RPM Calculator

Battery animation
Enter Kv value (RPM per Volt)
Enter applied voltage in volts

DC motor no-load speed can be estimated by multiplying the motor’s Kv rating (RPM per volt) with the applied voltage. This simple calculator instantly shows expected motor RPM based on your input values.

How DC motor RPM is calculated

Kv expresses how many revolutions per minute a motor spins per applied volt (no-load condition).
Formula: RPM = Kv × Voltage

Where this RPM calculation is useful

  • Electric bikes
  • RC brushless motors
  • Electric scooters
  • DIY EV projects

Limitations

This calculator provides no-load RPM. Real load (weight, friction, air resistance) will reduce actual RPM. Motor efficiency also affects real-world rotation speed.

Frequently Asked Questions

Q: Does RPM decrease under load?
Yes. The result here is theoretical no-load RPM. Real values are lower.
Q: Can I use any voltage?
Only within the motor’s rated operating voltage range.
Q: What if I don't know Kv?
You must know Kv, or refer to motor datasheet/specification.
Q: Does higher voltage increase RPM?
Yes. RPM rises linearly with applied voltage (under no load).
Q: Is this only for DC motors?
Suitable for DC and BLDC motors using Kv value (RPM/V).