Power Converter

Convert horsepower, kilowatts, watts, BTU per hour and tons of refrigeration.

Decimals, fractions (3 1/2) and e-notation (1.5e6) all work.
Common Conversions
Significant Digits
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Formula
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How to Convert Power Units

Power is energy per unit time; one watt is one joule per second. Mechanical horsepower is 550 foot-pounds per second, about 745.7 W.

kW = hp × 0.7457   BTU/h = W × 3.41214   1 ton = 12,000 BTU/h = 3.517 kW

Worked Example

Common Conversions

FromEquals
1 hp0.7456999 kW
1 kW1.341022 hp
1 W3.412142 BTU/h
1 BTU/h0.2930711 W
1 TR3.516853 kW
1 TR12,000 BTU/h
1 PS0.9863201 hp

Unit Definitions

UnitEqualsExact?
Watts (W)1 WExact
Kilowatts (kW)1,000 WExact
Megawatts (MW)1,000,000 WExact
Horsepower (mechanical) (hp)745.6998716 WExact
Metric horsepower (PS) (PS)735.49875 WExact
Electrical horsepower (hp(E))746 WExact
BTU per hour (BTU/h)0.2930710702 WExact
Tons of refrigeration (TR)3,516.852842 WExact
Foot-pounds per second (ft·lbf/s)1.355817948 WExact
Kilocalories per hour (kcal/h)1.162222222 WExact

Factors follow NIST Special Publication 811, Appendix B. "Exact" means the unit is defined as that value; results are rounded only for display.

Tips

European car specs often use metric horsepower (PS), about 1.4% smaller than US horsepower. Motor nameplates use 746 W per electrical horsepower.