Watt Conversion Calculator

Enter a value in watts below to convert to another unit of power.

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Do you want to convert watts to kilowatts or watts to horsepower?

What Is a Watt?

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A watt is a unit used to measure power.

The watt is the SI derived unit for power in the metric system. Watts can be abbreviated as W; for example, 1 watt can be written as 1 W.

Watt's Law states the relationship between power, current, and voltage. Using Watt's Law, it's possible to express the power in watts as an expression using current and voltage.

PW = IA × VV

The power in watts is equal to the current in amperes times the potential difference in volts.

Combining this with Ohm's Law, it's also possible to express the power in watts using resistance in addition to volts and amps.

Background and Origin

The watt is named after James Watt, a Scottish inventor who created the steam engine. The watt was proposed as a unit in 1882 by C. William Siemens, and formally adopted as the "international watt" in 1908 at the International Conference on Electric Units and Standards. In 1948 the watt was redefined to be based on absolute units rather than practical units, and is the definition of the unit we use today.

How Much Is a Watt?

One watt is the power equal to the rate of energy of one joule per second in an electrical circuit.[1] One watt is also equal to the power produced in a circuit with a voltage potential of one volt with a current of one amp.

How to Convert Watts

To convert watts to another unit of power, you need to multiply the value by a conversion factor. A conversion factor is a numerical value used to change the units of a measurement without changing the value.[2]

You can find the conversion factors for watts in the conversion table below.

Then, multiply the power measurement by the conversion factor to find the equivalent value in the desired unit of measurement.

watts × conversion factor = result

You can also use a calculator, such as one of the converters below, for the conversion.

Watt Conversion Table

Watts and the equivalent power measurements
watts microwatts milliwatts kilowatts megawatts horsepower btu per hour kilocalories per hour
1 W 1,000,000 µW 1,000 mW 0.001 kW 0.000001 MW 0.001341 hp 3.412142 Btu/h 0.860421 kcal/h
2 W 2,000,000 µW 2,000 mW 0.002 kW 0.000002 MW 0.002682 hp 6.824285 Btu/h 1.720842 kcal/h
3 W 3,000,000 µW 3,000 mW 0.003 kW 0.000003 MW 0.004023 hp 10.236427 Btu/h 2.581262 kcal/h
4 W 4,000,000 µW 4,000 mW 0.004 kW 0.000004 MW 0.005364 hp 13.64857 Btu/h 3.441683 kcal/h
5 W 5,000,000 µW 5,000 mW 0.005 kW 0.000005 MW 0.006705 hp 17.060712 Btu/h 4.302104 kcal/h
6 W 6,000,000 µW 6,000 mW 0.006 kW 0.000006 MW 0.008046 hp 20.472855 Btu/h 5.162525 kcal/h
7 W 7,000,000 µW 7,000 mW 0.007 kW 0.000007 MW 0.009387 hp 23.884997 Btu/h 6.022946 kcal/h
8 W 8,000,000 µW 8,000 mW 0.008 kW 0.000008 MW 0.010728 hp 27.29714 Btu/h 6.883367 kcal/h
9 W 9,000,000 µW 9,000 mW 0.009 kW 0.000009 MW 0.012069 hp 30.709282 Btu/h 7.743787 kcal/h
10 W 10,000,000 µW 10,000 mW 0.01 kW 0.00001 MW 0.01341 hp 34.121425 Btu/h 8.604208 kcal/h
11 W 11,000,000 µW 11,000 mW 0.011 kW 0.000011 MW 0.014751 hp 37.533567 Btu/h 9.464629 kcal/h
12 W 12,000,000 µW 12,000 mW 0.012 kW 0.000012 MW 0.016092 hp 40.945709 Btu/h 10.32505 kcal/h
13 W 13,000,000 µW 13,000 mW 0.013 kW 0.000013 MW 0.017433 hp 44.357852 Btu/h 11.185471 kcal/h
14 W 14,000,000 µW 14,000 mW 0.014 kW 0.000014 MW 0.018774 hp 47.769994 Btu/h 12.045891 kcal/h
15 W 15,000,000 µW 15,000 mW 0.015 kW 0.000015 MW 0.020115 hp 51.182137 Btu/h 12.906312 kcal/h
16 W 16,000,000 µW 16,000 mW 0.016 kW 0.000016 MW 0.021456 hp 54.594279 Btu/h 13.766733 kcal/h
17 W 17,000,000 µW 17,000 mW 0.017 kW 0.000017 MW 0.022797 hp 58.006422 Btu/h 14.627154 kcal/h
18 W 18,000,000 µW 18,000 mW 0.018 kW 0.000018 MW 0.024138 hp 61.418564 Btu/h 15.487575 kcal/h
19 W 19,000,000 µW 19,000 mW 0.019 kW 0.000019 MW 0.025479 hp 64.830707 Btu/h 16.347995 kcal/h
20 W 20,000,000 µW 20,000 mW 0.02 kW 0.00002 MW 0.02682 hp 68.242849 Btu/h 17.208416 kcal/h

Watt Conversion Calculators

You can also convert power using one of our watt converters below.

SI Units
US Customary & Imperial Units
Other Units
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You might also find our other electrical calculators useful.

References

  1. International Bureau of Weights and Measures, The International System of Units, 9th Edition, 2019, https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf
  2. National Institute of Standards & Technology, Unit Conversion, https://www.nist.gov/pml/owm/metric-si/unit-conversion

Other Power Units

SI Units
US Customary & Imperial Units
Other Units