The formula
kW = hp × 0.7456998716
Where the factor comes from — each unit by its definition, then its size in SI:
1 hp = 550 × ft·lbf / s = 745.699871582 W1 kW = 1000 × W = 1,000 W
Dividing the two SI sizes gives the factor: 0.745699871582 (rounded for display; the underlying ratio is fixed by the definitions). The reverse factor is 1.3410220896.
Power is energy per second; the watt is one joule per second. Engine ratings in horsepower and air-conditioner ratings in BTU/h convert to watts with fixed factors.
Worked examples
- A small car engine: 100 hp = 74.57 kW — 100 × 0.7456998716 = 74.57
- An old incandescent bulb (60 W): 0.0804613 hp = 0.06 kW — 0.0804613 × 0.7456998716 = 0.06
- An electric kettle: 2.68204 hp = 2 kW — 2.68204 × 0.7456998716 = 2
- A room air conditioner (12000 BTU/h): 4.71618 hp = 3.51685 kW — 4.71618 × 0.7456998716 = 3.51685
Frequently asked questions
How many kilowatts is 1 hp?
1 hp = 0.745699871582 kW.
How do I convert kilowatts back to horsepower (mechanical)?
Divide by 0.745699871582 — or multiply by 1.3410220896: 1 kW = 1.3410220896 hp.