Horsepower to kW Calculator
Enter horsepower to convert to kilowatts instantly. Uses the mechanical (imperial) HP standard: 1 HP = 0.7457 kW.
How do you convert horsepower to kilowatts?
Multiply HP by the conversion factor 0.7457: kW = HP × 0.7457. A 10 HP motor has a rated output of 10 × 0.7457 = 7.457 kW. This applies to the mechanical (imperial) horsepower where 1 hp = 745.7 W. Metric horsepower (PS/CV) is slightly smaller at 735.5 W; for metric HP use kW = PS × 0.7355.
HP to kW Conversion Table
| Horsepower (HP) | Kilowatts (kW) | Watts (W) |
|---|---|---|
| 0.5 HP | 0.373 kW | 372.9 W |
| 1 HP | 0.746 kW | 745.7 W |
| 2 HP | 1.491 kW | 1491.4 W |
| 5 HP | 3.729 kW | 3728.5 W |
| 10 HP | 7.457 kW | 7457.0 W |
| 15 HP | 11.186 kW | 11185.5 W |
| 25 HP | 18.643 kW | 18642.5 W |
| 50 HP | 37.285 kW | 37285.0 W |
| 100 HP | 74.570 kW | 74570.0 W |
Formula
Where: kW = kilowatts (mechanical output power), HP = mechanical (imperial) horsepower, 0.7457 = conversion factor (1 hp = 745.7 W = 0.7457 kW).
Note on variants: Metric horsepower (PS, CV, ch) = 735.5 W. Electrical horsepower = 746 W exactly (used in the US for motor nameplate ratings). The difference between metric and electrical HP is less than 0.1 %; for most practical calculations either factor is acceptable.
Standard Motor Ratings: US vs. International
In North America, industrial motors are sized in Horsepower (HP) following NEMA standards. In Europe and much of the world, they are sized in Kilowatts (kW) following IEC standards. Knowing the exact conversion helps when replacing imported equipment:
- 1 HP NEMA Motor ≈ 0.75 kW IEC Motor.
Since 1 HP is exactly 0.746 kW, the closest standard IEC metric motor size is 0.75 kW. They are effectively interchangeable if the physical mounting frames match. - 5 HP NEMA Motor ≈ 4.0 kW IEC Motor.
5 HP equals 3.73 kW. European manufacturers typically jump from 3.0 kW to 4.0 kW in standard frame sizes, so a 4.0 kW motor is the standard replacement. - 10 HP NEMA Motor ≈ 7.5 kW IEC Motor.
10 HP equals 7.46 kW. The standard 7.5 kW IEC motor is an almost perfect match in terms of output power.
Frequently Asked Questions
1 horsepower (mechanical) equals 0.7457 kW or 745.7 watts. This is the internationally recognised conversion factor for motor power ratings.
Mechanical (imperial) HP = 745.7 W, used in the US and UK. Metric HP (PS or CV) = 735.5 W, used in Europe for vehicle engines. For electric motors, the mechanical HP standard applies: kW = HP × 0.7457.
1 kW equals 1 ÷ 0.7457 ≈ 1.341 HP. Use the kW to HP calculator for the reverse conversion.
Motor HP ratings represent shaft output power — the mechanical power delivered to the load. Input power from the supply is higher because of motor losses; input kW = output kW ÷ efficiency. A 10 HP (7.457 kW output) motor at 92 % efficiency draws 7.457 ÷ 0.92 ≈ 8.1 kW from the supply.
Are IEC (kW) and NEMA (HP) motors directly interchangeable?
Electrically, yes—if you match the voltage, frequency, and equivalent power rating (e.g., 10 HP ≈ 7.5 kW). However, NEMA and IEC motors use entirely different physical frame sizes and shaft diameters, so they cannot bolt into the same mount without an adapter plate.