Horsepower to Watts Converter
Convert power units between Horsepower (Mechanical/Metric) and Watts. Essential for automotive and electrical engineering applications.
About
Confusion often arises in engineering between the two definitions of "Horsepower". Mechanical Horsepower (Imperial) is the standard in the US and UK automotive industries, while Metric Horsepower (PS, ch, cv) is used in Europe and Asia. The difference is approximately 1.4%, which is significant in high-performance or precision electrical applications. This tool bridges the gap between automotive specs (HP) and electrical ratings (Watts/kW), providing clarity and precision for engineers, mechanics, and enthusiasts.
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hp to kw
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metric horsepower
Formulas
The conversion depends on the specific definition of horsepower selected.
{
PW = Php × 745.699872 if MechanicalPW = Php × 735.49875 if Metric
Reference Data
| Power Unit | Symbol | Value in Watts (W) | Value in Kilowatts (kW) |
|---|---|---|---|
| Mechanical Horsepower | HP(I) | 745.6999 | 0.7457 |
| Metric Horsepower | HP(M) / PS | 735.4988 | 0.7355 |
| Electrical Horsepower | HP(E) | 746.0 | 0.7460 |
| Boiler Horsepower | HP(S) | 9,809.5 | 9.8095 |
Frequently Asked Questions
Mechanical HP originates from James Watt's experiments with steam engines and ponies in the 18th century (Imperial units). Metric HP was defined later to harmonize with the metric system, defined as the power to lift 75 kg by 1 meter in 1 second.
If the car is American or British, it likely uses Mechanical HP (SAE). If it is German (PS), Italian (CV), or French (ch), it uses Metric HP. The values are close but distinct.
You can use the "Switch Units" button in this tool. Mathematically, you divide the Watts by the constant (e.g., Watts / 745.7 = HP).
Roughly, yes. 746 W is the standard "Electrical Horsepower" used in US electrical codes for motor nameplates. However, for precise mechanical engineering, 745.7 (Imperial) or 735.5 (Metric) are the exact standards.