The formula
kW = PS × 0.73549875
Where the factor comes from — each unit by its definition, then its size in SI:
1 PS = 75 × kgf × m / s = 735.49875 W1 kW = 1000 × W = 1,000 W
Dividing the two SI sizes gives the factor: 0.73549875, exact — every step above is a definition, not a measurement. The reverse factor is 1.3596216173.
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): 101.387 PS = 74.57 kW — 101.387 × 0.73549875 = 74.57
- An old incandescent bulb (60 W): 0.0815773 PS = 0.06 kW — 0.0815773 × 0.73549875 = 0.06
- An electric kettle: 2.71924 PS = 2 kW — 2.71924 × 0.73549875 = 2
- A room air conditioner (12000 BTU/h): 4.78159 PS = 3.51685 kW — 4.78159 × 0.73549875 = 3.51685
Frequently asked questions
How many kilowatts is 1 PS?
1 PS = 0.73549875 kW, exactly, from the unit definitions.
How do I convert kilowatts back to metric horsepower?
Divide by 0.73549875 — or multiply by 1.3596216173: 1 kW = 1.3596216173 PS.