Hz to RPM Calculator
A hz to rpm calculator helps you quickly convert electrical frequency into motor speed. It is essential for engineers, technicians, and students working with motors and generators.
Frequency to Motor Speed Converter
How to Use Hz to RPM Calculator
Using a hz to rpm calculator is simple and practical. Follow these steps:
- Enter the frequency (Hz): Input the electrical frequency value (e.g., 50 Hz or 60 Hz).
- Enter the number of poles: Select the motor's pole count (e.g., 2, 4, 6, or 8 poles) from the nameplate.
- Click Calculate: The calculator instantly shows the RPM (rotations per minute).
- Review the result: Use the RPM value for motor selection, analysis, or troubleshooting.
Tips:
- Always confirm the pole number from the motor nameplate.
- Use standard frequencies like 50 Hz or 60 Hz for accurate results.
Conversion / Calculation Guide (Hz to RPM)
To convert Hz to RPM manually, use this standard formula:
Where:
- f = frequency in Hz
- P = number of poles
Step-by-Step Example
Let's calculate RPM for a motor:
Given:
- Frequency (f) = 50 Hz
- Poles (P) = 4
Step 1: Multiply frequency by 120
120 × 50 = 6000
Step 2: Divide by number of poles
6000 ÷ 4 = 1500 RPM
Final Answer: Motor speed = 1500 RPM
Hz to RPM Conversion Chart
Reference values for common frequency and pole combinations (synchronous speed):
| Frequency (Hz) | 2 Poles | 4 Poles | 6 Poles | 8 Poles |
|---|---|---|---|---|
| 50 Hz | 3000 RPM | 1500 RPM | 1000 RPM | 750 RPM |
| 60 Hz | 3600 RPM | 1800 RPM | 1200 RPM | 900 RPM |
| 25 Hz | 1500 RPM | 750 RPM | 500 RPM | 375 RPM |
| 100 Hz | 6000 RPM | 3000 RPM | 2000 RPM | 1500 RPM |
Note: These values represent synchronous speed. Actual motor speed may be slightly lower due to slip.
Frequently Asked Questions (FAQs)
A hz to rpm calculator converts electrical frequency into motor speed using the formula RPM = (120 × Frequency) ÷ Poles.
Pole count directly affects speed. More poles result in lower RPM for the same input frequency.
Use: RPM = (120 × Frequency) ÷ Poles. Multiply the frequency in Hz by 120, then divide by the number of motor poles.
The synchronous speed is 1500 RPM. Calculated as (120 × 50) ÷ 4 = 1500 RPM.
Synchronous speed is the ideal motor speed based on the supply frequency and pole count, calculated without considering any load losses.
Motors experience slip — the rotor runs slightly slower than the rotating magnetic field to generate torque. This reduces actual operating speed below the synchronous speed.
You can use it for AC motors, especially induction and synchronous motors. It is not applicable to DC motors, which use different speed control methods.
The synchronous speed is 3600 RPM. Calculated as (120 × 60) ÷ 2 = 3600 RPM.
Yes, RPM increases proportionally when frequency increases, assuming the number of poles remains constant.
It is used in motor design, electrical engineering, industrial applications, variable frequency drives (VFDs), and troubleshooting motor speed issues.