kW to HP conversion
The conversion between kilowatts (kW) and horsepower (HP) is fundamental in electrical, mechanical and automotive engineering. 1 kW equals 1,341 mechanical horsepower (hp or bhp) or 1,360 metric horsepower (CV or PS). For electrical applications, 1 hp is exactly defined as 746 W (0,746 kW), a reference value for sizing motors and equipment.
Conversion Formula
Section titled “Conversion Formula”The conversion formulas vary slightly depending on whether mechanical (imperial) or metric horsepower is used. Below are the direct equivalences and their inverses, using the most precise conversion factors.
Php(mec) = PkW × 1,34102209 Php(mét) = PkW × 1,35962162 PkW = Php(mec) × 0,74569987 PkW = Php(mét) × 0,73549875
Where:
- PkW : power in kilowatts (kW)
- Php(mec) : power in mechanical horsepower (hp, bhp, hp(I))
- Php(mét) : power in metric horsepower (CV, PS, hp(M))
Conversion Table
Section titled “Conversion Table”The following table lists conversion values between kilowatts and both types of horsepower, from fractions of kW to industrial powers. Each cell shows the value in mechanical hp followed by its metric hp equivalent.
| Kilowatts (kW) | Horsepower (hp mech / hp met) |
|---|---|
| 0,1 | 0,134 hp / 0,136 hp |
| 0,5 | 0,671 hp / 0,680 hp |
| 1 | 1,341 hp / 1,360 hp |
| 2 | 2,682 hp / 2,719 hp |
| 3 | 4,023 hp / 4,079 hp |
| 5 | 6,705 hp / 6,798 hp |
| 7,5 | 10,058 hp / 10,197 hp |
| 10 | 13,410 hp / 13,596 hp |
| 15 | 20,115 hp / 20,394 hp |
| 20 | 26,820 hp / 27,192 hp |
| 30 | 40,231 hp / 40,789 hp |
| 50 | 67,051 hp / 67,981 hp |
| 75 | 100,577 hp / 101,972 hp |
| 100 | 134,102 hp / 135,962 hp |
| 1000 | 1341,022 hp / 1359,622 hp |
Conversion Factors
Section titled “Conversion Factors”The exact conversion factors between kilowatts and the various horsepower definitions are fixed constants that do not depend on external conditions. They are summarized in the following table.
| From unit | To unit | Conversion factor |
|---|---|---|
| 1 kW | hp mechanical (imperial) | 1,34102209 |
| 1 kW | hp metric (CV/PS) | 1,35962162 |
| 1 hp mechanical | kW | 0,74569987 |
| 1 hp metric | kW | 0,73549875 |
Common Use
Section titled “Common Use”The kW–hp conversion is applied daily in the selection and comparison of electric motors, internal combustion engines, pumps, compressors and generator sets. In the industrial sector, standard electric motor power ratings stand out, with typical hp values such as 1, 1,5, 2, 3, 5, 7,5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100 and up to 4000 hp. These machines usually operate with voltages not exceeding 600 V AC and frequencies of 50 or 60 Hz. In automotive applications, many manufacturers express engine power in metric horsepower (CV) in Europe and in mechanical or SAE hp in the United States. The coexistence of both definitions makes it necessary to verify which one is being used before any technical comparison or energy calculation.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the difference between mechanical, metric and electrical horsepower?
Section titled “What is the difference between mechanical, metric and electrical horsepower?”Mechanical horsepower (imperial hp) equals 745,7 W, metric (CV or PS) equals 735,5 W, and electrical hp equals exactly 746 W. The difference between mechanical and metric is about 10 W, which is relevant when summing multiple machines. Electrical hp is used exclusively for electric motors.
How do I convert kW to hp for a three-phase motor?
Section titled “How do I convert kW to hp for a three-phase motor?”1 kW multiplied by 1,341 gives the power in mechanical hp, or by 1,360 for metric hp. The conversion is independent of the motor type; three-phase motors deliver shaft power that can be expressed in either unit using those factors.
Why are there multiple definitions of horsepower?
Section titled “Why are there multiple definitions of horsepower?”James Watt’s original definition (1782) was based on the force of a draft horse, resulting in 33,000 lb·ft/min (746 W). Over time regional variants emerged: continental Europe adopted the metric horsepower (75 kg·m/s, 735,5 W), while the UK and USA kept the imperial. Electrical hp was fixed at exactly 746 W to simplify calculations.
How many kW does a horsepower have?
Section titled “How many kW does a horsepower have?”One mechanical horsepower has 0,7457 kW, one metric horsepower 0,7355 kW, and one electrical horsepower 0,746 kW. These figures allow conversion in both directions with sufficient precision for most technical applications.
What formula should I use to convert kW to hp in Europe?
Section titled “What formula should I use to convert kW to hp in Europe?”In Europe, metric horsepower (CV or PS) predominates. Therefore, the recommended formula is to multiply kilowatts by 1,3596. Thus, 100 kW equals 135,96 CV. However, in product technical specifications it is advisable to verify whether the manufacturer uses metric or mechanical hp.
Does the kW‑hp conversion factor change with temperature or altitude?
Section titled “Does the kW‑hp conversion factor change with temperature or altitude?”No. The conversion factors (1,341 and 1,360) are fixed dimensionless constants that reflect the relationship between the power units and do not depend on environmental conditions. A motor’s power does vary with temperature or altitude, but the unit conversion remains the same.
References
Section titled “References”- engineeringtoolbox.com: https://www.engineeringtoolbox.com/electrical-motor-horsepower-d_653.html
- unitconverters.net: https://www.unitconverters.net/power/kw-to-hp.htm
- convertworld.com: https://www.convertworld.com/en/power/kilowatt/kw-to-hp.html