kW to HP Calculator

About the kW to HP Calculator

This kW to HP calculator converts kilowatts to horsepower across all three common definitions: mechanical (US Imperial), electrical, and metric (PS, used in Europe). Use it to cross-reference NEMA and IEC motor catalogs, size replacement motors when sourcing across markets, or interpret European motor nameplates against North American specifications.

Defaults match the 745.7 watts per mechanical HP used in most Canadian and US industrial applications. Adjust the conversion type when working with European specifications or precision engineering applications.

How kW to HP conversion works

The conversion factor depends on which horsepower definition you use:

HP (mechanical) = kW × 1.341
HP (electrical) = kW × 1.340
PS (metric) = kW × 1.3596

The differences come from how horsepower was historically defined: mechanical HP equals 745.7 watts (33,000 ft-lb/min, the original 1782 James Watt definition); electrical HP rounds to 746 watts for motor ratings; metric horsepower (PS, “Pferdestärke”) equals 735.5 watts and is the standard in continental Europe.

Worked example

An IEC-rated 5 kW motor converts to 5 × 1.341 = 6.71 mechanical HP. When sourcing a NEMA equivalent, you would round up to a 7.5 HP motor since 6.71 HP is not a standard NEMA frame size. The next standard size below would be 5 HP, which is 6.7% undersized — risky for continuous duty.

When to use this calculator

• Cross-referencing IEC (kW-rated) and NEMA (HP-rated) motor catalogs when sourcing replacements
• Sizing replacement motors when the only rating on the nameplate is in the wrong unit
• Specifying motors for international projects with mixed metric/imperial requirements
• Verifying VFD output power against the connected motor rating
• Matching pump or fan curves rated in kW to HP-rated drive systems
• Quick reference during inspection, troubleshooting, or technical sales conversations

NEMA vs IEC standards

The split between kW and HP ratings reflects different regulatory traditions: NEMA (National Electrical Manufacturers Association) standards govern motors sold in North America and rate output in horsepower per NEMA MG-1. IEC (International Electrotechnical Commission) standards govern most of the rest of the world and rate output in kilowatts per IEC 60034. Both describe the same shaft mechanical power — the only difference is the unit and minor rounding to standard sizes.

Standard NEMA sizes: 1/8, 1/6, 1/4, 1/3, 1/2, 3/4, 1, 1.5, 2, 3, 5, 7.5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 200, 250, 300, 350, 400, 450, 500 HP. Standard IEC sizes: 0.06, 0.09, 0.12, 0.18, 0.25, 0.37, 0.55, 0.75, 1.1, 1.5, 2.2, 3, 4, 5.5, 7.5, 11, 15, 18.5, 22, 30, 37, 45, 55, 75, 90, 110, 132, 160, 200, 250, 315, 355 kW.

Frequently Asked Questions

How do you convert kW to HP?

Multiply kilowatts by 1.341 to get mechanical horsepower, or by 1.340 for electrical horsepower. For metric horsepower (PS), multiply by 1.3596. Example: 5 kW × 1.341 = 6.71 HP mechanical.

What is the difference between mechanical and electrical HP?

Mechanical HP equals exactly 745.7 watts — the historical James Watt definition based on 33,000 ft-lb/min. Electrical HP rounds to 746 watts and is the value used in NEMA motor nameplate ratings. The difference is 0.04% — negligible for sizing purposes.

What is metric horsepower (PS)?

Metric horsepower, abbreviated PS (German “Pferdestärke”), equals 735.5 watts. It’s the standard in continental Europe and is roughly 1.4% smaller than mechanical HP. Don’t confuse it with kW — it’s still horsepower, just defined differently.

How many HP is 5 kW?

5 kW equals 6.71 mechanical HP, 6.70 electrical HP, or 6.80 metric HP (PS). For practical motor sizing, treat all three as roughly 6.7 HP; for NEMA sourcing you would step up to a standard 7.5 HP motor.

Why are motors rated in kW outside North America?

Most countries follow IEC standards, which use SI units (kilowatts). North America’s NEMA standards predate the SI system and have retained horsepower ratings for industrial motors. Both standards now coexist, with many motors carrying dual ratings on their nameplates.

Should I size a motor by kW or HP?

Use whichever unit your application or specification requires. They describe the same shaft mechanical power — convert with this calculator and source the closest standard size. NEMA buyers typically specify in HP; IEC buyers in kW; OEMs designing for global markets often spec both.

Are kW and kVA the same thing?

No. kW is real power (mechanical work output). kVA is apparent power (total electrical input). The relationship: kW = kVA × power factor. For a typical motor at 0.85 PF, 10 kVA input produces about 8.5 kW of usable mechanical output.

kW to HP Conversion Table (Common Values)

Quick reference for converting common kilowatt motor ratings to mechanical horsepower (1 kW = 1.341 HP). For an exact figure including efficiency and power factor, use the calculator above.

Common kW to HP Conversions

How do I convert kW to HP?

Multiply the kilowatt value by 1.341 to get mechanical horsepower. For example, 10 kW × 1.341 = 13.41 HP. For metric horsepower (PS, used in Europe) multiply by 1.3596, and for electrical horsepower multiply by 1.340.

What is 10 kW in HP?

10 kW equals 13.41 mechanical HP (10 × 1.341). The nearest standard NEMA motor size would be 15 HP.

What is 37 kW in HP?

37 kW equals 49.6 mechanical HP (37 × 1.341). 37 kW is a standard IEC motor rating; its closest NEMA equivalent is 50 HP.

What is 75 kW in HP?

75 kW equals 100.6 mechanical HP (75 × 1.341). This maps almost exactly to a 100 HP NEMA motor.

What is 600 kW in HP?

600 kW equals 804.6 mechanical HP (600 × 1.341). At this size, motors are typically specified in kW even in North America and are medium-voltage units.

Cómo convertir kW a HP (kW a HP en español)

Para convertir kilovatios a caballos de fuerza (HP), multiplique el valor en kW por 1.341. Por ejemplo, 10 kW × 1.341 = 13.41 HP. Este conversor kW a HP funciona para motores monofásicos, trifásicos y de corriente continua.

Related calculators and motor categories

Looking for the right motor after running your conversion? Browse Electracore’s stock of General Purpose motors, Explosion Proof motors, or HVAC motors — from leading brands including Baldor, WEG, Marathon, and U.S. Motors.

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