Power Converter

Which power units are available?

Watts, kilowatts, megawatts, mechanical horsepower, metric horsepower (PS), BTU per hour and calories per second. The watt is the base unit, equal to one joule per second.

Is a horsepower 745.7 watts or 746 watts?

It depends on the definition. The mechanical (imperial) horsepower, 550 foot-pounds-force per second, is 745.69987158 W, which this tool uses and which rounds to 745.7. The electrical horsepower used for motor ratings is set at exactly 746 W, so a rating of 1 hp can differ by about 0.04 percent between standards.

What is the difference between hp and PS?

Metric horsepower, written PS, CV or hk, is the power to raise 75 kg through 1 m in a second: exactly 735.49875 W. It is about 1.4 percent smaller than the mechanical horsepower, so 100 PS is 98.632 hp. Car makers in Europe usually quote PS.

Why does 1 hp show as 745.6998716 W and not 745.7?

The tool keeps the full definition of mechanical horsepower, 745.69987158227 W, rather than the rounded figure. The same applies to metric horsepower (735.49875 W) and BTU/h (0.29307107 W), so round trips such as W to hp and back stay consistent.

Which BTU does BTU per hour use?

The International Table BTU, so 1 BTU/h is 0.29307107 W and 1 kW is 3,412.141635 BTU/h. Air-conditioner capacity in BTU/h converts the same way; 12,000 BTU/h is one ton of refrigeration and equals 3.51685284 kW.

What is calories per second here?

It uses the thermochemical calorie of 4.184 J, so 1 cal/s equals 4.184 W. This is the small calorie, not the food Calorie (kcal), which is 1,000 times bigger. Be careful when reading nutrition-related figures.

Is power the same as energy?

No. Power is the rate: watts, kilowatts, horsepower. Energy is power over time, such as kilowatt-hours or joules. A 2 kW heater running for an hour uses 2 kWh. This tool converts power only, not energy.