Convert horsepower (mechanical) to kilowatt.

About this conversion

Horsepower-to-kilowatts: multiply by 0.7457. The standard conversion when reading car specs, machinery ratings, and industrial equipment between US and metric markets.

Formula

kW = hp × 0.7457

Real-world examples

Reference values

Tips & tricks

• Three different "horsepower" definitions exist: mechanical (745.7 W, US/UK), metric (735.5 W, European PS/CV), and boiler (9809.5 W, rarely used). Most car specs use mechanical.
• European cars are often spec'd in PS (Pferdestärke, metric HP) which is 1.4% lower than mechanical HP. A "200 PS" engine is 197 mechanical HP.
• Electric motor ratings are typically in kW. Tesla's Model S Plaid puts out 760 kW (≈ 1020 HP).

Origin & history

James Watt defined horsepower in 1782 to market his improved steam engine to mine owners who measured output in "how many horses' work" the engine replaced. The kilowatt followed naturally from the SI definition of the watt (1 J/s).

What is a horsepower (mechanical)?

One mechanical horsepower equals about 745.7 watts. The "metric horsepower" (PS, CV) is slightly different at 735.5 W. Engine output ratings (cars, motorcycles, lawnmowers), pump ratings, and industrial machinery.

What is a kilowatt?

One kilowatt equals exactly 1,000 watts. Larger motors, EV charging speeds, home solar arrays, and HVAC systems.

What does hp look like in everyday objects?

These anchors can be useful when sizing up a value. 1 hp is roughly the sustained power output of a fit cyclist; 100 hp is a small economy car; and 500 hp is a high-performance sports car.

How to convert horsepower (mechanical) to kilowatt

To convert a value from horsepower (mechanical) (hp) to kilowatt (kW), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in hp.
2. Apply the formula see formula above.
3. The result is your value in kW.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert hp to kW?

Apply the formula hp → kW shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, hp or kW?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then kW is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then kW is the larger unit.

When would I use hp versus kW?

Both units measure power, so the choice depends on context. Horsepower (mechanical) is typically used for engines, electrical loads, and HVAC equipment; kilowatt similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this hp to kW conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

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See also