Watts (W) to Horsepower (hp) Conversion

Watts

The watt (W) is the SI derived unit of power, defined as one joule per second (J/s = kg·m²·s⁻³), representing the rate of energy transfer or conversion. Named after Scottish engineer James Watt, whose steam engine improvements launched the Industrial Revolution, the watt is the coherent unit for all forms of power — mechanical, electrical, thermal, and acoustic. A human at rest produces about 80 W of thermal power; a professional cyclist sustains approximately 400 W during a race; a lightning bolt peaks at around 10¹² W for microseconds.

Horsepower

Horsepower (hp) is a unit of power originally defined by James Watt in the 1780s to market steam engines against the work output of draft horses. The US mechanical horsepower equals exactly 745.69987158 watts. Multiple definitions exist: mechanical hp (745.7 W), metric hp (735.5 W), and electrical hp (746 W). In the automotive industry, engine power is expressed in horsepower in the US and UK markets, where 1 hp ≈ 0.7457 kW.

Convert Watts (W) to other units of Power