Convert Watts to Mechanical Horsepower

Convert Watts (W) to Mechanical Horsepower (hp) instantly and accurately.

Conversion Formula

hp = W × 0.00134102209

About Watts

The watt (W) is the SI unit of power - 1 J/s - named after James Watt (1736-1819). Familiar power levels: smartphone charging 5-65 W; laptop 15-100 W; microwave 700-1,200 W; electric kettle 2,000-3,000 W; human resting metabolism ~80 W; peak sprint ~2,000 W. The now-obsolete 100 W incandescent bulb is replaced by a 10-15 W LED producing the same light. In AC circuits, reactive power uses the var and apparent power the VA, both derived from watts. 1 W = 1 J/s = 1 kg·m²/s³.

About Mechanical Horsepower

The mechanical horsepower (hp) is exactly 550 ft·lbf/s ≈ 745.7 W - defined by James Watt by timing mine horses to set a comparable steam engine rating. A typical compact car produces 100-150 hp (75-112 kW); a sports car 300-600 hp; an F1 car ~1,000 hp (745 kW). SAE net horsepower is measured at the flywheel with all accessories fitted. Marine diesel engines, aircraft piston engines, and lawn equipment are still rated in hp. 1 hp = 550 ft·lbf/s = 745.6998715822704 W.

Quick Reference Table

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