HP to kW Converter: Horsepower to Kilowatts
Convert horsepower to kilowatts (and back) instantly, with the exact definitions engineers use: 1 mechanical hp = 0.745699872 kW, 1 metric PS = 0.73549875 kW. Free, no sign-up, works offline.
Live converter
Convert HP to kW
Also converts: horsepower to kW, kW to hp, hp to watts, watts to hp, PS to hp, hp to PS, PS to kW, kW to PS, and BTU/h — pick any two units above.
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Definitions
Not all horsepower is the same
Four different units share the name "horsepower". Car, motor and boiler specs may use different ones — always check which one you are converting.
Mechanical horsepower — hp (I)
550 foot-pounds-force per second. The imperial definition from James Watt's steam-engine era, standardized through the international foot and pound (NIST SP 811). The default "hp" in the US and UK.
Metric horsepower — PS / hp (M)
Exactly 75 kilogram-force metres per second. The standard for engine ratings across Europe and Asia (German Pferdestärke, French cheval-vapeur). About 1.4% smaller than mechanical hp.
Electrical horsepower — hp (E)
Exactly 746 watts by convention (IEEE). Used on electric motor nameplates in North America. Only 0.04% larger than mechanical hp, so the two are interchangeable in practice.
Boiler horsepower — bhp
The power to evaporate 34.5 lb of water per hour at 212 °F — about 33,475 BTU/h (≈ 9.81 kW; published conventions range 9,809.5–9,812.5 W, this page uses 9,812.5 W). A steam-boiler rating, not a measure of shaft or engine power.
Quick reference
HP to kW tables
Common values at a glance. The converter above handles any value with full precision.
| HP | kW | PS |
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| kW | HP | PS |
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Worked examples
How the conversion works
Example 1: 100 hp to kW
- Use the mechanical horsepower definition:
1 hp = 0.745699872 kW - Multiply:
100 × 0.745699872 = 74.5699872 kW - Answer: 100 hp = 74.57 kW (rounded)
Example 2: 150 kW to hp (electric car motor)
- Invert the factor:
1 kW = 1 ÷ 0.745699872 = 1.3410220888 hp - Multiply:
150 × 1.3410220888 = 201.1533133 hp - Answer: 150 kW = 201.15 hp, usually quoted as 201 hp
Example 3: 150 PS to kW and hp (European engine)
- Metric horsepower is smaller:
1 PS = 0.73549875 kW - To kilowatts:
150 × 0.73549875 = 110.3248125 kW - To mechanical hp:
150 × 0.98632007 = 147.948 hp - Answer: 150 PS = 110.32 kW = 147.95 hp
In the real world
Where hp to kW comes up
Electric vehicles
EV makers publish motor power in kilowatts (the electric unit), while buyers still think in horsepower. A 150 kW motor is a 201 hp motor; a 300 kW dual-motor setup is 402 hp.
European EV specs often use PS instead: 150 kW = 203.94 PS.
Car and bike engines
US brochures quote mechanical hp, European ones quote PS. The same 300 hp engine is listed as 304.16 PS in Germany — identical engine, different unit.
Remember: brochure figures are crankshaft (brake) horsepower; wheel horsepower is 10–20% lower after drivetrain losses.
Air conditioners & motors
AC capacity is quoted in BTU/h (12,000 BTU/h = 3.5169 kW of cooling), while compressor motors are rated in hp or kW. A 3.5 kW compressor motor is a 4.69 hp motor.
Small workshop motors are sold by kW in metric countries and by hp in the US — the same conversion, every time.
Scope boundary: what this tool does (and does not) do
- This tool converts power units — hp, PS, kW, watts, BTU/h. Type a number, get the same physical power in another unit.
- Estimating an engine's horsepower from torque and RPM, quarter-mile ET and trap speed, or an engine build sheet is a different job: use the Horsepower Calculator, a dedicated 6-method automotive HP lab.
- Other power units (dBm, megawatts, gigawatts, calories/second and more): use the Power Unit Converter hub with 19 units.
- hp to electric current needs voltage too (I = P ÷ V): see HP to Amps. Power relative to weight: Power-to-Weight Ratio.
FAQ
HP to kW questions, answered
How many kilowatts (kW) is 1 horsepower?
One mechanical horsepower equals exactly 0.745699872 kW (745.699872 watts). So 10 hp is 7.457 kW, 50 hp is 37.285 kW, and 100 hp is 74.570 kW. If you mean metric horsepower (PS), 1 PS is 0.73549875 kW instead.
What is the formula to convert hp to kW?
Multiply horsepower by 0.745699872: kW = hp x 0.745699872. For example, 100 hp x 0.745699872 = 74.5699872 kW, usually rounded to 74.57 kW. The factor comes from the definition of mechanical horsepower: 550 foot-pounds per second.
How do I convert kW to hp?
Multiply kilowatts by 1.341022: hp = kW x 1.341022. For example, 150 kW x 1.341022 = 201.15 hp. This is the conversion EV makers use in reverse: a motor rated 150 kW is advertised as roughly a 201 hp motor.
What is the difference between mechanical horsepower and metric horsepower (PS)?
Mechanical horsepower (hp) is 745.699872 W, defined as 550 ft-lbf/s. Metric horsepower (PS, from German Pferdestarke) is 735.49875 W, defined as exactly 75 kgf-m/s. They differ by about 1.4 percent: 1 hp = 1.01387 PS, and 1 PS = 0.98632 hp. PS is the standard for engine ratings in Europe and most of Asia.
How many watts are in 1 horsepower?
One mechanical horsepower is 745.699872 watts. One metric horsepower (PS) is 735.49875 watts, and one electrical horsepower is exactly 746 watts. For quick estimates, 3/4 of a kilowatt (750 W) per horsepower is close enough.
What is electrical horsepower?
Electrical horsepower, written hp(E), is defined as exactly 746 watts. It is the convention used on electric motor nameplates in North America. It is only 0.04 percent larger than mechanical horsepower (745.699872 W), so the two are interchangeable for most practical purposes.
How do I convert PS to hp?
Multiply PS by 0.98632: hp = PS x 0.98632. For example, a European engine rated 150 PS equals 150 x 0.98632 = 147.95 hp, and 150 PS equals 110.32 kW. Going the other way, multiply hp by 1.01387 to get PS.
How many BTU per hour is 1 horsepower?
One mechanical horsepower equals 2,544.43 BTU/h. One kilowatt equals 3,412.14 BTU/h. This conversion is handy for air conditioners and heaters, where capacity is often quoted in BTU/h but motors are rated in hp or kW.
What is boiler horsepower?
Boiler horsepower is a steam-era rating: the power needed to evaporate 34.5 pounds of water per hour at 212 F, conventionally rated at 33,475 BTU/h — about 9.81 kW. Published conventions vary slightly (9,809.5–9,812.5 W); this tool uses 9,812.5 W. It measures boiler output, not shaft power, so do not confuse it with engine horsepower.
My EV is rated at 150 kW - how many horsepower is that?
150 kW equals 201.15 hp of mechanical horsepower (150 x 1.341022), usually quoted as 201 hp. In metric PS it is 203.94 PS. EV manufacturers publish kilowatts because the motor is electric; horsepower is the same physical power expressed in the older unit.
Why does the same car show different power figures in the US and Europe?
The US quotes mechanical horsepower while Europe quotes metric PS, and 1 hp = 1.01387 PS. A car rated 300 hp in the US is rated 300 x 1.01387 = 304.16 PS in Europe. It is the same engine - only the unit changed.
How many horsepower is a 3.5 kW motor?
3.5 kW x 1.341022 = 4.69 hp of mechanical horsepower. Small motors are often sold by kW in metric countries and by hp in the US, so this conversion comes up constantly when replacing pumps, compressors, and workshop tools.
Is brake horsepower (bhp) the same as hp?
The unit is the same - bhp is still measured in horsepower. The word brake only says where it was measured: at the engine crankshaft on a dynamometer brake, before gearbox and drivetrain losses. Wheel horsepower (whp) is lower because of those losses, typically by 10 to 20 percent.
How many kW is 200 hp? What about 450 hp?
200 hp x 0.745699872 = 149.14 kW. A 450 hp V8 is 450 x 0.745699872 = 335.56 kW. Use the converter above for any value, or the quick tables for common engine sizes.
Can this tool calculate my engine's horsepower from torque and RPM?
No - this page only converts between power units (hp, kW, PS, watts). To estimate an engine's horsepower from torque and RPM, quarter-mile times, or an engine build sheet, use the Horsepower Calculator at nrtechstudio.com/tools/horsepower-calculator/, which is a dedicated automotive HP lab.
Where can I convert other power units like dBm, megawatts, or calories per second?
Use the Power Unit Converter at nrtechstudio.com/tools/power-unit-converter/. It covers 19 power units including dBm, MW, GW, BTU/h, and cal/s. This page stays focused on the horsepower family (mechanical, metric PS, electrical, boiler) against watts and kilowatts.
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