When selecting an industrial air compressor, understanding the electric motor’s power rating is essential to ensure your electrical grid can handle the load. If you are comparing equipment from European and North American manufacturers, having a reliable kW to HP converter is a must. While the US standardizes motor size in HP (Horsepower), metric systems specify power in kW (Kilowatts). Read our quick guide below, and use our interactive tool to translate your electrical requirements instantly.
Motor Power Converter
How to Convert kW to HP (Formula)
If you are looking at a European DIN-standard compressor datasheet and need to determine the mechanical horsepower, you will use the standard multiplier.
Formula:
HP = kW × 1.341
Example:
If an industrial screw compressor is driven by a 37 kW motor:
- 37 × 1.341 = ~49.6 HP (Usually rounded to an industry-standard 50 HP).
How to Convert HP to kW (Formula)
If you need to size the electrical breakers for a North American machine, you must convert the mechanical horsepower back to electrical kilowatts. Rather than doing manual math, our kW to HP converter allows you to type in the HP and instantly get the precise kW load.
Formula:
kW = HP × 0.7457
Example:
If your shop runs a classic 10 HP piston compressor:
- 10 × 0.7457 = 7.457 kW (Standardized as a 7.5 kW motor globally).
Motor Power vs. Compressor Output
It is vital not to confuse the motor power (HP/kW) with the actual performance of the air compressor.
- Power (kW / HP) tells you how much electricity the motor consumes.
- Airflow (CFM / m³/h) tells you how much usable air the machine generates. (Need to calculate airflow? Use our CFM to m³/h Converter).
- Pressure (psi / bar) tells you the force of that air. (Check out our psi to bar Converter to calculate pressure).
The Expert Factor: Service Factor (SF)
When comparing American HP motors and European kW motors, you must consider the Service Factor (SF).
Many North American compressor motors feature a Service Factor of 1.15 or 1.25. This means a 100 HP motor with a 1.15 SF can safely deliver up to 115 HP continuously. In contrast, European IEC metric motors (rated in kW) usually operate at a 1.0 SF, meaning a 75 kW motor is designed to provide exactly 75 kW—and no more. Always check the motor nameplate before finalizing your electrical sizing!
Quick Reference: Industrial Motor Sizes
Here is a quick reference table showing the most common motor sizes used in industrial air compressors:
| Metric Standard (kW) | Imperial Equivalent (HP) | Typical Compressor Type |
| 2.2 kW | 3 HP | Small Garage / Piston |
| 4.0 kW | 5.5 HP | Auto Shop Piston |
| 7.5 kW | 10 HP | Small Rotary Screw |
| 15 kW | 20 HP | Medium Workshop |
| 37 kW | 50 HP | Industrial Manufacturing |
| 75 kW | 100 HP | Heavy Duty Plant Air |
| 160 kW | 215 HP | Large Scale Production |
Frequently Asked Questions (FAQ)
What does 1 HP equal in kW?
One mechanical horsepower (HP) is equal to 0.7457 kilowatts (kW).
Are kW and kVA the same thing?
No. Kilowatts (kW) represent “real power” that performs actual work. kVA (Kilovolt-Amps) represents “apparent power,” which factors in the power factor of the electrical system. Our kW to HP converter deals strictly with real mechanical motor power.
Does a higher HP mean more CFM?
Generally, yes. For standard industrial air compressors operating at 100 psi, you can expect roughly 4 to 5 CFM per 1 HP. However, the exact efficiency depends heavily on the airend design and compressor type (piston vs. rotary screw).