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Power converter

Watts, kilowatts, megawatts, mechanical and metric horsepower, BTU per hour, kcal per hour and tons of refrigeration.

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Fromhorsepower (mechanical, 550 ft·lbf/s) (hp)
1
Tokilowatt (kW)
0.7456998716
DecimalsAuto (up to 10 significant digits)

Formula: kW = hp × 0.745699871582

1 hp = 0.7456998716 kW

Common values: horsepower (mechanical, 550 ft·lbf/s) to kilowatt

hpkW
1 hp0.7456998716 kW
5 hp3.728499358 kW
10 hp7.456998716 kW
50 hp37.28499358 kW
100 hp74.56998716 kW
150 hp111.8549807 kW
200 hp149.1399743 kW
300 hp223.7099615 kW
500 hp372.8499358 kW
1,000 hp745.6998716 kW

How it works

Car engines are rated in kW in EU type approval documents, in horsepower in the US and in PS (metric horsepower) in German and Japanese brochures. Air conditioners are sold by BTU per hour or tons of refrigeration, and appliances by watts. This converter puts them on one scale.

Mechanical horsepower is 550 foot-pounds per second, 745.700 W; metric horsepower (PS, CV, pk) is 75 kilogram-force metres per second, exactly 735.49875 W, so 100 PS is 98.6 hp. One ton of refrigeration is 12,000 BTU/h, about 3.517 kW of cooling. These are derived from the exact foot, pound, standard gravity and International Table BTU.

Power is a rate. To get energy, multiply by time: a 1.5 kW kettle running for 4 minutes uses 0.1 kWh.

Common power conversions

Engine power is quoted in kW, mechanical horsepower (hp) or metric horsepower (PS), which differ by about 1.4%. Air conditioners are rated in BTU per hour or tons of refrigeration (12,000 BTU/h).

  • 1 hp = 0.7456998716 kW (kW = hp × 0.745699871582)
  • 1 kW = 1.34102209 hp (hp = kW × 1.3410220896)
  • 1 PS = 0.73549875 kW (kW = PS × 0.73549875)
  • 1 BTU/h = 0.2930710702 W (W = BTU/h × 0.293071070172)
  • 1 TR = 3.516852842 kW (kW = TR × 3.51685284207)
  • 1 kW = 3,412.141633 BTU/h (BTU/h = kW × 3,412.14163313)

Every power unit in this converter

The size of each unit in watts (W), the base unit the converter uses internally. Values are exact where the unit has an exact definition.

UnitIn W
watt (W)1 W
kilowatt (kW)1,000 W
megawatt (MW)1,000,000 W
horsepower (mechanical, 550 ft·lbf/s) (hp)745.6998716 W
metric horsepower (PS, 75 kgf·m/s) (PS)735.49875 W
BTU per hour (BTU/h)0.2930710702 W
kilocalorie per hour (kcal/h)1.162222222 W
ton of refrigeration (12,000 BTU/h) (TR)3,516.852842 W

How to use it

  1. Pick the power unit you have and the one you want.
  2. Type the value in either box.
  3. Use the table for common engine or air-conditioner ratings.

Frequently asked questions

How many kW is 1 hp?

1 mechanical hp = 0.7457 kW, and 1 kW = 1.341 hp. A 150 kW engine is about 201 hp or 204 PS.

What is the difference between hp and PS?

PS (Pferdestärke, metric horsepower) is 735.5 W; mechanical (imperial) horsepower is 745.7 W, about 1.4% more. European brochures quote PS; US ones quote hp.

How many kW is a 12,000 BTU air conditioner?

12,000 BTU/h is one ton of refrigeration, about 3.52 kW of cooling capacity. The electrical input is lower, divided by the unit's efficiency (EER or COP).

Is BTU the same as BTU per hour?

Not strictly. BTU is energy; BTU/h is power. AC units are marketed as "12,000 BTU" but mean BTU per hour.

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