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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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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.

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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