Kilowatts to Horsepower (kW to HP) Converter

The Kilowatts to Horsepower (kW to HP) Converter is the essential tool for engineers, technicians, and buyers who need to translate power specifications from the SI metric system into the horsepower ratings that remain standard in North American equipment markets, automotive specifications, and legacy industrial catalogs. Whether you are selecting a motor, evaluating an imported machine, or comparing a European engine to its American counterpart, this converter provides instant, accurate results.

The kilowatt (kW) is the internationally standardized unit of power under the International System of Units (SI), defined as exactly 1000 joules per second. It is the preferred unit in IEC electrical standards, European motor nameplates, energy billing, and scientific literature worldwide. Horsepower, by contrast, is a unit with deep historical roots in British and American engineering — defined by James Watt in the 1780s as 550 foot-pounds of work per second (33,000 ft·lbf/min), it remains the dominant unit for motor ratings in the United States and for automotive power in many English-speaking markets.

Converting kW to HP is a daily task in several professional contexts. Motor purchasing agents sourcing international equipment must verify that a 75 kW IEC motor meets the same service requirements as the 100 HP NEMA motor it replaces. Automotive journalists translating European car reviews convert PS (metric HP) to brake horsepower for American readers. Mechanical engineers designing systems to ASME standards must express IEC motor ratings in HP for compliance with NEMA tables referenced in NEC Article 430. HVAC engineers converting chiller ratings between kW/ton and HP/ton need this conversion as an intermediate step.

The conversion formula is straightforward: HP = kW ÷ conversion factor. The conversion factor depends on which type of horsepower you need:

• Mechanical HP: 1 HP = 0.74569987 kW, so HP = kW / 0.7457. This is the correct factor for general engineering in the US customary system.
• Metric HP (PS/CV/pk/ch): 1 PS = 0.73549875 kW, so HP = kW / 0.73550. Use this when dealing with European automotive specs or DIN-standard equipment.
• Electrical HP: 1 HP = exactly 0.746 kW, so HP = kW / 0.746. The NEC and NEMA use this definition for motor circuit calculations.
• Boiler HP: 1 BHP = 9.8095 kW, so HP = kW / 9.8095. Used only for steam boiler capacity ratings.

Common conversions that engineers frequently perform: 37 kW = 49.6 HP (standard IEC motor size that corresponds to the NEMA 50 HP frame); 75 kW = 100.6 HP; 110 kW = 147.5 HP; 132 kW = 177 HP; 160 kW = 214.6 HP; 200 kW = 268.3 HP; 250 kW = 335.4 HP. These IEC-to-NEMA equivalents are essential for motor interchangeability studies and upgrade projects.

The foot-pounds per second output provides an additional mechanical context: it expresses power in the original units that James Watt used when defining horsepower, offering a tactile understanding of the mechanical work being performed. For example, 10 kW equals approximately 7,376 ft·lbf/s — the equivalent of lifting 7,376 one-pound weights through one foot each second, simultaneously.

When using converted values for electrical system design, remember that motor efficiency and power factor affect actual electrical power consumption. The HP or kW rating is the shaft output; electrical input will be higher by the reciprocal of motor efficiency. Always apply the appropriate NEC table full-load current values rather than calculated values when sizing motor branch circuits, per NEC 430.6(A)(1).