Power Converter – Watt, Horsepower & Kilowatt

One mechanical/imperial horsepower (hp) equals exactly 745.699872 watts. This is the most widely used definition in the United States and the automotive industry. In many engineering fields, this is often rounded to 746 W for convenience. Metric horsepower (also called PS or CV) is slightly lower at approximately 735.5 watts, but our tool uses the mechanical horsepower standard.

To convert kilowatts (kW) to mechanical horsepower (hp), multiply the kilowatt value by 1.34102209 (since 1 kW = 1000 W and 1 hp = 745.699872 W). For example, 100 kW is equal to 134.102209 hp. Conversely, to convert horsepower to kilowatts, multiply by 0.745699872.

Yes, several definitions of horsepower exist: Mechanical/Imperial horsepower (≈ 745.7 W) used mainly in the U.S. and UK for car engines; Metric horsepower (PS, CV, or ch) ≈ 735.5 W used in Europe; Electrical horsepower defined as exactly 746 W; and Boiler horsepower equal to 9,812.5 W. This converter relies on the mechanical horsepower standard for all calculations.

James Watt introduced the term “horsepower” in the late 18th century as a marketing tool to compare steam engines to draft horses, making the technology relatable to a pre‑industrial audience. The watt was later adopted as the SI unit of power in his honor. Today, watts dominate electrical and scientific contexts while horsepower remains entrenched in automotive, marine, and mechanical engineering communities.

Our tool uses precise conversion factors: 1 watt = 0.001 kilowatt, 1 horsepower = 745.699872 watts (exact). All conversions are performed with high precision and results are rounded to a maximum of six decimal places. This ensures practical accuracy for engineering, automotive, and everyday calculations.