Power Converter is a converter used to convert power from one power unit into another. The good news is, our power converter supports all the common and popular units of power. Because of its ease of use, you should definitely check it out and have it on your phone.

While here, see other conversion related tools on our site, such as Quantity Converter, Torque to hp Calculator, Million to Lakh Converter. Besides these already mentioned, learn more conversions with the following calculators: Px to Em Converter, Acreage Calculator, Force Converter, or maybe this Oz to Cups Converter and PPM Calculator as well.

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Power units

By default, we define power as an amount of electric energy or any other energy transferred in a certain period of time. We have plenty of different power units, so you will get familiar with the most common units of power and their definitions in this section.


The standard and the most used unit of power is a watt. It indicated how much energy we need to supply to an item to work and function properly. For example, we use watts a lot for RV power converters. RV power converters are used for converting 120-volt AC power to 12-volt DC power. Generally, power converters increase or decrease the magnitude of the input voltage, or we use them as a polarity inverter.

BTU per Hour

BTU per Hour is a heat power unit. It equals the amount of heat needed to supply to raise one pound of water by 1 ℉.

BTU per Second

BTU per Second is a unit of power that does not belong to the SI metric system.

Foot Pound per Second

Foot Pound per Second (ft-lb/s) is another non-SI unit of power.

Calories per Second

Equivalents to how many calories are released per second to do specific work.


Horsepower equals the power that engines produce. Additionally, it indicates how much energy we need to supply to move 550 pounds one foot in one second or 33,000 pounds one foot in one minute.

What is a watt?

Watt is a unit of power that was introduced to the system of metrics by an engineer James Watt. Furthermore, its name was taken from the surname of this engineer. Generally, it measures the rate at which energy is being transferred. Watts as a unit of power indicated how much current energy we need to do particular work at a given time. For example, a person with 80 kg weight running on a 100-meter pitch in 20 seconds is doing the work at a rate of 125 Watts or 125 volt at given 1 amp. Voltage of 1 unit is equal to 1 watt if the amp circuit is 1, too.

1 Watt = \frac{1 kgm^{2}}{s^{3}}

So, as the equation above tells us, 1 Watt is equal to the amount of a person’s weight multiplied by the square of the work to be done and dividing the result by cube of the seconds needed to complete the work.

The symbol for a watt is 1 W (Watt).

What about electronic home devices? What do you think how much power or voltage do current devices you have at home need to work properly? For example, an air cooler has power consumption of between 65 and 80 W. On the other hand, a hair dryer consumes around 1500 watts. Similarly, all world plug types (small or large plugs) have different voltage (voltage input) and are used for different adapters. A single battery inverter needs 150 to 350 Watts to recharge a battery from 0 to 100%. Electrical energy is can be transferred without changing its voltage by a power transformer.

Fun fact: Do you know at what speed does electrical power travel? Believe me or not, 670,616,629 miles per hour.

People easily mix and misunderstand Watt with Watt-Hour. Their names are pretty similar, so it doesn’t surprise us. However, there is the main difference between these two units. On one hand, Watt is a unit of power, and it indicates the rate at which the work is done. On the other hand, Watt-Hour is a unit of energy, and it tells us how much work is done, not the rate.

SI multiples for watt (W)

Watt is a standard and default unit of power. However, there are many derivations of Watt, so in the list below, you can see all the SI multiples for Watt (W). We group them into two: multiples (units bigger than 1 Watt) and submultiples (units smaller than 1 Watt)

SI Derivation Units for Watt (W):

  • Yoctowatt – one septillionth (10−24) of a watt.
  • Zeptowatt – one sextillionth (10−21) of a watt.
  • Attowatt – quintillionth (10−18) of a watt.
  • Femtowatt – one quadrillionth (10−15) of a watt. Indeed, this unit has appliances in radio and radar receivers.
  • Picowatt – one trillionth (10−12) of a watt. For instance, acoustics and radio astronomy use this unit.
  • Nanowatt – one billionth (10−9) of a watt.
  • Microwatt – one millionth (10−6) of a watt. Namely, microwatts are used in medical instrumentation systems and compact solar power system.
  • Milliwatt – one thousandth (10−3) of a watt. For example, audio and electronic signals are measured in milliwatts.
  • Kilowatt – one thousand (103) watts. For example, we use kilowatts to express the power of engines, machines and electromagnetic force.
  • Megawatt – one million (106) watts.
  • Gigawatt – one billion (109) watts. For instance, gigawatts have appliances in measuring the power of large power plants and energy grid or electric grid.
  • Terawatt – to one trillion (1012) watts. For example, one lighting strikes travel is equal to 1 Terawatt.
  • Petawatt – one quadrillion (1015) watts. Such as, the sun’s striking Earth is calculated to be equal to 174 Petawatts.

History of the term “horsepower”

The term “horsepower” dates back to the 18th century, when horses were the primary tool for any kind of heavy work. Thus, James Wat, an engineer, wanted to find a way to sell his steam engine.

horsepower - unit of power

So he made a test using a mine pony because mining was vastly popular back then, and he found out that one mine pony can handle 22,000 pound-feet of work in a minute. However, James went further and decided to use a full-sized horse for the test. Eventually, he came back with the results that a full-size horse can perform a lot more work than a mine pony, 33,000 pound-feet of work in a minute. That is the background story of how the term “horsepower” came into use.

Horsepower and its types

When we measure power, we can express it as horsepower. However, this is not the only type of horsepower, because we have several others, as well:

  • Mechanical horsepower
  • Metric horsepower
  • Electrical horsepower
  • Boiler horsepower
  • Hydraulic horsepower
  • Air horsepower

Power conversion chart

Watt (joules/s) (W)1000Milliwatt (mW)
Watt (joules/s) (W)0.001Kilowatt (kW)
Watt (joules/s) (W)0.000001Megawatt (MW)
Watt (joules/s) (W) 1e^{-9}Gigawatt (GW)
Watt (joules/s) (W) 0.001341022089595 Horsepower (hp)
Watt (joules/s) (W) 0.2388458966275Calories per Second (cal/s)
Watt (joules/s) (W) 10000000Erg per Second (erg/s)
Watt (joules/s) (W) 0.7375621492773Foot Pound per Second (ft lb/s)
Watt (joules/s) (W) 0.0009478169879134BTU per Second (BTU/s)
Watt (joules/s) (W) 3.412141156488BTU per Hour (BTU/h)
Horsepower (hp)745,699.8715823Milliwatt (mW)
Horsepower (hp)745.6998715823Watt (Joules/Second) (W)
Horsepower (hp)0.7456998715823Kilowatt (kW)
Horsepower (hp)0.0007456998715823Megawatt (MW)
Horsepower (hp)7.456998715823e^{-7}Gigawatt (GW)
Horsepower (hp)178.1073544431Calories per Second (cal/s)
Horsepower (hp)7,456,998,715.823Erg per Second (erg/s)
Horsepower (hp)550Foot Pound per Second (ft lb/s)
Horsepower (hp)0.7067870061706BTU per Second (BTU/s)
Horsepower (hp)2544.433222214BTU per Hour (BTU/h)
Calories per Second (cal/s)4186.8Milliwatt (mW)
Calories per Second (cal/s)4.1868Watt (Joules/Second) (W)
Calories per Second (cal/s)0.0041868Kilowatt (kW)
Calories per Second (cal/s)0.0000041868Megawatt (MW)
Calories per Second (cal/s)4.1868e^{-9}Gigawatt (GW)
Calories per Second (cal/s)0.005614591284716Horsepower (hp)
Calories per Second (cal/s)41,868,000Erg per Second (erg/s)
Calories per Second (cal/s)3.088025206594Foot Pound per Second (ft lb/s)
Calories per Second (cal/s)0.003968320164996BTU per Second (BTU/s)
Calories per Second (cal/s)14.28595259399BTU per Hour (BTU/h)
Erg per Second (erg/s)0.0001Milliwatt (mW)
Erg per Second (erg/s)1e^{-7}Watt (Joules/Second) (W)
Erg per Second (erg/s)1e^{-10}Kilowatt (kW)
Erg per Second (erg/s)1e^{-13}Megawatt (MW)
Erg per Second (erg/s)1e^{-16}Gigawatt (GW)
Erg per Second (erg/s)1.341022089595e^{-10} Horsepower (hp)
Erg per Second (erg/s)2.388458966275e^{-8}Calories per Second (cal/s)
Erg per Second (erg/s)7.375621492773e^{-8}Foot Pound per Second (ft lb/s)
Erg per Second (erg/s)9.478169879134e^{-11}BTU per Second (BTU/s)
Erg per Second (erg/s)3.412141156488e^{-7}BTU per Hour (BTU/h)
Foot Pound per Second (ft lb/s)1355.817948331Milliwatt (mW)
Foot Pound per Second (ft lb/s)1.355817948331Watt (Joules/Second) (W)
Foot Pound per Second (ft lb/s)0.001355817948331Kilowatt (kW)
Foot Pound per Second (ft lb/s)0.000001355817948331Megawatt (MW)
Foot Pound per Second (ft lb/s)1.355817948331e^{-9}Gigawatt (GW)
Foot Pound per Second (ft lb/s)0.001818181818182Horsepower (hp)
Foot Pound per Second (ft lb/s)0.3238315535329Calories per Second (cal/s)
Foot Pound per Second (ft lb/s)13,558,179.48331Erg per Second (erg/s)
Foot Pound per Second (ft lb/s)0.001285067283946BTU per Second (BTU/s)
Foot Pound per Second (ft lb/s)4.626242222207BTU per Hour (BTU/h)
BTU per Second (BTU/s)1,055,056Milliwatt (mW)
BTU per Second (BTU/s)1055.056Watt (Joules/Second) (W)
BTU per Second (BTU/s)1.055056Kilowatt (kW)
BTU per Second (BTU/s)0.001055056Megawatt (MW)
BTU per Second (BTU/s)0.000001055056Gigawatt (GW)
BTU per Second (BTU/s)1.41485340176Horsepower (hp)
BTU per Second (BTU/s)251.9957963122Calories per Second (cal/s)
BTU per Second (BTU/s)10,550,560,000Erg per Second (erg/s)
BTU per Second (BTU/s)778.1693709679Foot Pound per Second (ft lb/s)
BTU per Second (BTU/s)3600BTU per Hour (BTU/h)
BTU per Hour (BTU/h)293.0711111111Milliwatt (mW)
BTU per Hour (BTU/h)0.2930711111111Watt (Joules/Second) (W)
BTU per Hour (BTU/h)0.0002930711111111Kilowatt (kW)
BTU per Hour (BTU/h)2.930711111111e^{-7}Megawatt (MW)
BTU per Hour (BTU/h)2.930711111111e^{-10}Gigawatt (GW)
BTU per Hour (BTU/h)0.0003930148338221Horsepower (hp)
BTU per Hour (BTU/h)0.06999883230895Calories per Second (cal/s)
BTU per Hour (BTU/h)2,930,711.111111Erg per Second (erg/s)
BTU per Hour (BTU/h)0.2161581586022Foot Pound per Second (ft lb/s)
BTU per Hour (BTU/h)0.0002777777777778BTU per Second (BTU/s)
Units of Power Conversion Chart

Power conversions 

We see all the multipliers we need to know before converting from one power unit to another in the chart above. Therefore, let’s take two random power units and convert them in the example below.

Example: Convert 30 horsepower (hp) to calories per second (cal/s)

The conversion multiplier for hp to cal/s is: 178.1073544431

30 \times 178.1073544431 = 5343.22

Thus, 30 (hp) is equal to 5343.22 (cal/s).

Power converter – how to use

The best choice when converting power units is to use our power converter. What does our power converter do? All you need to do is choose a unit of power you want to convert from and it will make the power transformer do the conversion of it into several other power units that you specify beforehand.

Example: Convert 500 Watts to milliwatts, air horsepowers, BTU/h, erg/s and kcal/min using our power converter


Step 1 – Enter the power in watts in the calculator (power size selection)

Step 2 – Select the power units you want to calculate watts to and then leave the power converter do the magic

500 Watts:

  • 50,000 mW
  • 0.37 ahp
  • 1,706 BTU/h
  • 1,812,560,427.53 erg/s
  • 7.17 kcal/min

Other systems units in the calculator

If you are interested in the list of all available system units that our power converter calculator supports, refer to the list below:

  • Watt (including all Watt derivations such as milliwatts, kilowatts, terawatts and more)
  • Horsepower (mechanical, metric, electric and air horsepowers)
  • British Thermal Units per hour (BTU / h)
  • Kilocalories per minute (kcal / min)
  • Kilocalories per hour (kcal / h)
  • Ergs per second (ergs / s)
  • Ton of refrigerator (TR)