Unit Conversion: How to Convert HP to kW

Unit conversions in electrical engineering are very important, it is relatively easy, but it can also cause many problems when planing or troubleshooting systems.

HP to kW conversion is very important when 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.

hp to kw conversion 1

How to Calculate HP to kW?

Both HP and kW 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!

HP to kW Conversion Chart

The following HP to kW 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.