Engine power is advertised in horsepower in the United States and in kilowatts — often with metric horsepower alongside — in Europe, Australia and most of Asia. Electric motors, generators and EV drive units are rated in kW almost everywhere. This converter turns horsepower into kilowatts and shows how much the answer moves depending on which horsepower definition a spec sheet is using.
How to use the hp to kW converter
- Enter the power in Horsepower (hp) — the mechanical (imperial) horsepower used in US specs.
- Read the result in kilowatts, with watts and metric horsepower below.
- The energy row shows how many kWh the machine would use or deliver in one hour at full power.
- The definitions table repeats the conversion for metric, electrical and boiler horsepower, in case your figure uses one of those.
Horsepower to kW formula
James Watt set the horsepower at 33,000 foot-pounds of work per minute, which is 550 ft·lbf per second. With 1 ft = 0.3048 m and 1 lbf = 4.4482216152605 N, that is:
For a quick estimate, multiply horsepower by ¾ — the result is about 0.6% high.
Worked example
A pickup truck’s V8 is rated at 300 hp.
300 × 0.745699872 = 223.71 kW.
Quick estimate: 300 × 0.75 = 225 kW.
In metric horsepower: 223.71 kW ÷ 0.73549875 = 304.2 PS — European ads for the same engine would quote about 304 PS.
Second case, an outboard motor: a 25 hp engine is 25 × 0.7457 = 18.6 kW.
Four kinds of horsepower
| Definition | Watts per hp | Where you see it |
|---|---|---|
| Mechanical (imperial) hp | 745.70 | US and UK engines, tools |
| Metric hp (PS, CV, pk) | 735.50 | European and Japanese cars |
| Electrical hp | 746 | Motor nameplates (NEMA) |
| Boiler hp | 9,809.5 | Steam boiler output |
The first three are within about 1.5% of each other, so the label usually matters only for precise comparisons. Boiler horsepower is a different animal: it measures the rate of steam production, roughly 13 times a mechanical horsepower.
Gross, net, brake and wheel horsepower
- Gross ratings, common in the US before 1972, measured a bare engine without accessories and exhaust.
- Net ratings (SAE J1349 in the US) test the engine with its production intake, exhaust and accessories, so they are lower and more realistic.
- Brake horsepower is measured at the crankshaft on an engine dynamometer.
- Wheel horsepower, from a chassis dyno, is typically 10–20% below crank figures because of drivetrain losses.
All are in the same unit; they differ in where and how the power is measured.
Electric motors and EVs
An electric motor’s kW rating is its output power, and the electrical input is higher by the motor’s losses. A 7.5 kW (about 10 hp) industrial motor at 92% efficiency draws roughly 8.2 kW from the supply. EV makers quote peak motor output in kW; dividing by 0.7457 gives the horsepower figure US marketing uses.
To convert in the other direction, use kW to hp. For BTU per hour, tons of refrigeration and other power units, see the power converter. If you know torque and rpm instead of power, the torque converter computes the power directly.
Frequently asked questions
How many kW is 1 horsepower?
One mechanical horsepower is 0.7457 kW (745.7 watts). It is defined as 550 foot-pounds per second, which works out to 745.69987 W.
What is 300 hp in kW?
223.7 kW, because 300 × 0.7457 = 223.71. If the 300 is metric horsepower (PS), the answer is 220.6 kW instead.
Is bhp the same as hp?
Brake horsepower (bhp) is power measured at the engine's crankshaft, in the same mechanical-horsepower unit. Wheel horsepower, measured on a chassis dyno, is lower because the transmission and drivetrain lose some power.
Why do car brochures list both kW and PS?
European regulations require engine power in kilowatts, and many manufacturers add metric horsepower (PS or CV) because buyers know it. 100 kW is 136 PS but only 134 mechanical hp.