Unit Conversion: How to Convert Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP)
Unit conversions in electrical engineering are very important, it is relatively easy, but it can also cause many problems when planning or troubleshooting systems.
Horsepower to kilowatts (HP to kW) and kilowatts to horsepower (kW to HP) conversions are very important when the energy and power of internal combustion engines are compared or transferred between energy and power of electric motors, pumps, winches, inverters, and other devices being powered by electric energy.
Updated: December 7, 2021.
On This Page:
- Conversion Formulas - How to Convert HP to kW and kW to HP?
- HP to kW and kW to HP Conversion Examples
- HP to kW and kW to HP Conversion Calculator
- HP to kW and kW to HP Conversion Chart
- Standard SI Prefixes
Conversion Formulas - How to Convert HP to kW and kW to HP?
Both horsepower (HP) and kilowatt (kW, sometimes written "kilo-watt") are units that measure the power of a system. As a power unit, the 'HP' (Horse Power) has a long history that is beyond the scope of this article (and this site) - it is enough to say that the unit was used to measure the strength of a horse, hence the name, and compare it with the strength of early steam engines.
Today, HP as a unit is mostly used for describing/rating the strength or power of various engines (internal combustion engines, steam turbines, and similar).
On the other hand, 'watt' is an SI unit and is exactly defined.
There are several definitions of HP, but the most used one define:
1 HP = 746 W
Since SI prefix 'kilo' (shortened to 'k') means thousand (or 103), it also means that:
1 HP = 746 W = 0.746 kW
Likewise:
1 kW = 1/0.746 HP = 1.34048 HP ≈ 1.34 HP
For short:
1 HP = 0.746 kW → P (kW) = 0.746 * P (HP)
1 kW = 1.34 HP → P (HP) = 1.34 * P (kW)
So, if You have value in HPs, multiply it with 0.746 or divide it with 1.34 and You will get the equivalent value in kW (kilowatts) - in most situations, a calculator app on the computer or smartphone can do the job, but sometimes a common calculator can come very handy!
Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP) Conversion Examples
Here are several HP to kW and kW to HP conversion examples:
0.5 HP to kW: P (kW) = 0.746 * P (HP) = 0.746 * 0.5 = 0.373 kW = 373 W
1 HP to kW: P (kW) = 0.746 * P (HP) = 0.746 * 1 = 0.746 kW = 746 W
5 HP to kW: P (kW) = 0.746 * P (HP) = 0.746 * 5 = 3.73 kW = 3730 W
50 HP to kW: P (kW) = 0.746 * P (HP) = 0.746 * 50 = 37.3 kW = 37300 W
100 HP to kW: P (kW) = 0.746 * P (HP) = 0.746 * 100 = 74.6 kW = 74600 W
1 kW to HP: P (HP) = 1.34 * P (kW) = 1.34 * 1 = 1.34 HP
1.5 kW to HP: P (HP) = 1.34 * P (kW) = 1.34 * 1.5 = 2.01 HP = ~2 HP
7.5 kW to HP: P (HP) = 1.34 * P (kW) = 1.34 * 7.5 = 10.05 HP = ~ 10 HP
200 kW to HP: P (HP) = 1.34 * P (kW) = 1.34 * 200 = 268 HP = ~270 HP
300 kW to HP: P (HP) = 1.34 * P (kW) = 1.34 * 300 = 402 HP = ~400 HP
Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP) Conversion Calculator
In order to convert Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP), feel free to use this conversion calculator - write the value that You have and click 'Calculate' to convert it:
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Horsepower to Kilowatts |
Kilowatts to Horsepower |
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HP: kW: |
kW: HP: |
Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP) Conversion Chart
The following Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP) conversion chart lists power, currents, and voltages of specific loads:
| Power (HP) | Power (kW - kilowatts) |
Current @ Nominal Voltage | ||||
| 12 Volts | 24 Volts | 36 Volts | 120 Volts | 230 Volts | ||
| 0.335 HP | 0.25 kW | 20.83 A | 10.41 A | 6.94 A | 2.083 A | 1.087 A |
| 0.67 HP | 0.5 kW | 41.67 A | 20.83 A | 13.89 A | 4.167 A | 2.174 A |
| 1 HP | 0.746 kW | 62.16 A | 31.08 A | 20.72 A | 6.216 A | 3.243 A |
| 1.34 HP | 1 kW | 83.33 A | 41.66 A | 27.78 A | 8.333 A | 4.238 A |
| 1.5 HP | 1.119 kW | 93.25 A | 46.62 A | 31.08 A | 9.325 A | 4.865 A |
| 2 HP | 1.492 kW | 124.3 A | 62.16 A | 41.44 A | 12.43 A | 6.487 A |
| 2.0107 HP | 1.5 kW | 125 A | 62.5 A | 41.66 A | 12.5 A | 6.521 A |
| 2.5 HP | 1.865 kW | 155.4 A | 77.71 A | 51.81 A | 15.41 A | 8.108 A |
| 2.68 HP | 2 kW | 166.6 A | 83.3 A | 55.5 A | 16.66 A | 8.695 A |
| 3 HP | 2.238 kW | 186.5 A | 93.25 A | 62.16 A | 18.65 A | 9.730 A |
| 4 HP | 2.984 kW | 248.6 A | 124.3 A | 82.88 A | 24.86 A | 12.97 A |
| 4.021 HP | 3 kW | 250 A | 125 A | 83.33 A | 25 A | 13.04 A |
| 5 HP | 3.73 kW | 310.8 A | 155.4 A | 103.6 A | 31.08 A | 16.21 A |
| 5.3619 HP | 4 kW | 333.3 A | 166.6 A | 111.1 A | 33.33 A | 17.39 A |
| 6 HP | 4.476 kW | 373 A | 186.5 A | 124.3 A | 37.3 A | 19.46 A |
| 6.70 HP | 5 kW | 416.6 A | 208.3 A | 138.8 A | 41.6 A | 21.74 A |
| 7.5 HP | 5.595 kW | 466.2 A | 233.1 A | 155.4 A | 46.6 A | 24.33 A |
| 10 HP | 7.460 kW | 621.6 A | 310.8 A | 207.2 A | 62.1 A | 32.43 A |
| 13.40 HP | 10 kW | 833.3 A | 416.6 A | 277.8 A | 83.3 A | 43.48 A |
For example, if You want to convert 5 HP to kW, check the chart:
- 5 HP equals to 3.73 kW, or 310.8 Amps @12 volts, 155.4 Amps @24 volts, 103.6 Amps @36 volts, 31.08 Amps @120 volts, and 16.21 Amps @230 volts.
Standard SI Prefixes
SI prefixes are used in order to write down very large or very small numbers - after all, it is much easier to write, for example, 25 kW than 25000 watts. But, it is also much easier to write 25 MW than 25000 kW or 25000000 watts.
The following chart lists the International System of Units (SI) official prefixes:
| Prefix | Base 10 | Decimal | English Word | ||
| Name | Symbol | Short Scale | Long Scale | ||
| yotta | Y | 1024 | 1 000 000 000 000 000 000 000 000 | septillion | quadrillion |
| zetta | Z | 1021 | 1 000 000 000 000 000 000 000 | sextillion | trilliard |
| exa | E | 1018 | 1 000 000 000 000 000 000 | quintillion | trillion |
| peta | P | 1015 | 1 000 000 000 000 000 | quadrillion | billiard |
| tera | T | 1012 | 1 000 000 000 000 | trillion | billion |
| giga | G | 109 | 1 000 000 000 | billion | milliard |
| mega | M | 106 | 1 000 000 | million | |
| kilo | k | 103 | 1 000 | thousand | |
| hecto | h | 102 | 100 | hundred | |
| deca | da | 101 | 10 | ten | |
| - | - | 100 | 1 | one | |
| deci | d | 10-1 | 0.1 | tenth | |
| centi | c | 10-2 | 0.01 | hundredth | |
| milli | m | 10-3 | 0.001 | thousandth | |
| micro | μ | 10-6 | 0.000 001 | millionth | |
| nano | n | 10-9 | 0.000 000 001 | billionth | milliardth |
| pico | p | 10-12 | 0.000 000 000 001 | trillionth | billionth |
| femto | f | 10-15 | 0.000 000 000 000 001 | quadrillionth | billiardth |
| atto | a | 10-18 | 0.000 000 000 000 000 001 | quintillionth | trillionth |
| zepto | z | 10-21 | 0.000 000 000 000 000 000 001 | sextillionth | trilliardth |
| yocto | y | 10-24 | 0.000 000 000 000 000 000 000 001 | septillionth | quadrillionth |
Note: the 'Short Scale' is in use in, for example, the United States, while the 'Long Scale' is in use in, for example, Europe.
Long Story Short: Unit conversions, including HP to kW and back, are easy, just be sure to remember right formulas:
1 HP = 0.746 kW → P (kW) = 0.746 * P (HP)
1 kW = 1.34 HP → P (HP) = 1.34 * P (kW)
And don't forget to use the calculator, especially for larger values.
