How to Convert Hertz to Motor RPM Quickly and Accurately

By Kim Lewis

Updated: Feb. 27, 2025 3:30 pm EST

Filippo Carlot/Shutterstock

Frequency describes oscillatory motion, such as the vibrations of a motor or the wave of a signal. It is measured in hertz, meaning one cycle per second. Revolutions per minute (RPM) measures how many full turns an object makes around an axis each minute. For an electric motor, the no‑load speed is often expressed in hertz, and converting it to RPM is essential for design, troubleshooting, and performance tuning.

Step 1: Identify the Motor’s Frequency

Start with the motor’s frequency in hertz. For example, if a motor runs at 65 Hz, it completes 65 full cycles every second.

Step 2: Apply the Conversion Factor

Because one minute contains 60 seconds, each hertz corresponds to 60 revolutions per minute.

Step 3: Perform the Calculation

Multiply the frequency by 60. Using the example, 65 Hz × 60 = 3 900 RPM.

Reverse Conversion

To find hertz from RPM, divide the RPM value by 60.

References

Physics Principles with Applications, Douglas Giancoli
University Physics, Richard Wolfson