Battery Equivalents and Replacements

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: February 14, 2024.

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, including:

Mechanic or hydraulic horsepower (HP): one mechanic or hydraulic horsepower equals 745.699872 W or 0.745699872 kW:

1 HPI = 745.699872 W = 0.745699872 kW

Electrical horsepower (HP): one electrical horsepower equals exactly 746 W or 0.746 kilowatts:

1 HPE = 746 W = 0.746 kW

Metric horsepower (HP): one metric horsepower equals 735.49875 W or 0.73549875 kilowatts:

1 HPM = 735.49875 W = 0.73549875 kW

There are other HP definitions, including tax horsepower, drawbar horsepower, boiler horsepower, etc., but the most used one is electrical horsepower, which defines:

1 HP = 746 W

Since the 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 by 0.746 or divide it by 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 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 (Note: electric horsepower is assumed):

Horsepower to Kilowatts

HP:

kW:

 

Kilowatts to Horsepower

kW:

HP:


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 Table

The following Horsepower to Kilowatts (HP to kW) and Kilowatts to Horsepower (kW to HP) conversion table lists the power, currents, and voltages of specific loads:

Power (HP) Power (kW) 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 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
quetta Q 1030 1 000 000 000 000 000 000 000 000 000 000 nonillion quintillion
ronna R 1027 1 000 000 000 000 000 000 000 000 000 octillion quadrilliard
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
ronto r 10-27 0.000 000 000 000 000 000 000 000 001 octillionth quadrilliardth
quecto q 10-30 0.000 000 000 000 000 000 000 000 000 001 nonillionth quintillionth

Note: the 'Short Scale' is in use in, for example, the United States, while the 'Long Scale' is in use in, for example, Europe.

hp to kw w600px

kW to HP and HP to kW Conversion Frequently Asked Questions (FAQ)

Here are some of the most common Frequently Asked Questions (FAQ) about kilowatts to horsepower and horsepower to kilowatts conversion:

Is 1 HP equal to 1 kW? How many kW is equal to 1 HP?

No, 1 HP equals 746 Watts or 0.746 kW - although there are many other definitions for HP, this one is called "Electric Horsepower" and is the most common one and is very similar to "Mechanical Horsepower," which is 745.69987W.

Metric Horsepower, also often labeled as PS (German for "Pferdestärke," horsepower, shorted to PS) equals 735.49875W. Note that there are even more definitions like Boiler Horsepower (9812.5W), Hydraulic Horsepower (745.69987W), Air Horsepower (745.69987), etc.

What is the formula of kW to HP? How many kW is equal to 1 HP?

The formula is 1 kW = 1/0.746 HP = 1.34048257 HP

How many HP is 15 kW?

P(HP) = 15 kW * 1.34 = ~20.1 HP


Long Story Short: Unit conversions, including HP to kW and back, are easy, just be sure to remember the 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. Again, these values are for electric horsepower.