What Is A Watt Kilowatt?

A watt and a kilowatt are two units of power measurement in the International System of Units (SI). A watt measures the rate of energy conversion or transfer, while a kilowatt equals 1000 watts. In this article, we will define what a watt and kilowatt are, explain the relationship between these two units, and discuss their history and usage.

Watt Definition

The watt is the standard international unit used to measure power. Power refers to the rate at which energy is transferred or converted over time. For example, a 100-watt light bulb uses 100 joules of energy per second. This means that in one second, the light bulb converts 100 joules of electrical energy into light and heat energy.

The watt unit was named after Scottish engineer James Watt, who helped improve the efficiency of steam engines during the Industrial Revolution. His work led to significant advancements in measuring power output. The watt unit became an internationally adopted standard unit of power in 1960. It is commonly used today to measure the power consumption of electrical devices and appliances.

Kilowatt Definition

The kilowatt is equal to 1000 watts. It is commonly used to express power on a large scale, such as the output of engines and power plants.

The kilowatt provides a convenient way to express large amounts of power that would be cumbersome in watts. For example, the output of a power plant may be hundreds or thousands of megawatts.

Since the kilowatt is equal to 1000 watts, if you know the number of kilowatts you can easily convert it to watts by multiplying by 1000. For example, a 5 kilowatt electric heater would produce 5000 watts of heating power.

The kilowatt is part of the International System of Units (SI) and has the symbol kW. It helps bridge the scale between the watt and larger units like the megawatt (MW) and gigawatt (GW).

Watt vs Kilowatt

Watts and kilowatts are both units used to measure power, but they represent different amounts.

A watt is a smaller unit, defined as 1 joule per second. A kilowatt is equal to 1000 watts. This means a kilowatt is 1000 times larger than a watt.

Some examples comparing watt and kilowatt usage:

  • A standard lightbulb uses about 60 watts of power
  • An electric stove may use 1-5 kilowatts depending on the heating element
  • A laptop computer uses between 15-100 watts
  • An air conditioner may use 1-5 kilowatts depending on its size and settings

As you can see from the examples, kilowatts are used to measure larger amounts of power, like that required by major appliances. Watts measure smaller everyday amounts of electricity usage, like lightbulbs or consumer electronics.

To convert between the two, just remember that 1 kilowatt = 1000 watts. So 1 kilowatt would be equivalent to 1000 watts, and similarly, 1 watt would be equivalent to 0.001 kilowatts.

Watt History

The watt unit of power is named after James Watt, the Scottish inventor and mechanical engineer. In the late 18th century, James Watt helped improve the design of the steam engine and played a major role in popularizing it during the Industrial Revolution.

Watt determined that one horsepower was equivalent to about 746 watts. So the watt unit was defined in his honor as equal to one joule (a unit of energy) per second. This established the watt as a measurement of power, which is defined as the rate at which energy is converted or work is done.

So the origin of the watt unit stems from James Watt’s pivotal work on steam engines and early power generation. His improvements to engine efficiency and capacity helped drive the use of steam power during the Industrial Revolution. By quantifying power output in terms of watts as a consistent unit, Watt facilitated the widespread adoption of steam engines in factories, mills, and transportation.

an old photo of james watt next to a steam engine

Kilowatt History

The term “kilowatt” entered use in the late 19th century with the development and commercialization of electric power systems. As electricity became more widely adopted to power homes, businesses, and industries, a standard unit was needed to measure electrical power usage.

The kilowatt unit was formally adopted at the International Electrical Congress held in Chicago in 1893. The Congress decided to follow the metric system prefixes for units of electrical power, so “kilowatt” was coined as a unit equal to 1000 watts.

The kilowatt quickly caught on among electrical engineers and power companies as a convenient way to denote power capacity and consumption. Power plants were described in kilowatts of generating capacity. Motors, heaters, lights, and other electrical equipment had power ratings expressed in kilowatts.

By the early 20th century, kilowatt had become the standard unit for billing electricity usage. Power companies determined rates per kilowatt-hour, allowing customers’ energy consumption to be easily calculated and charged. The kilowatt era had begun, establishing the unit as essential for the electrical age.

Watt Usage

The watt is commonly used to measure the power consumption of household appliances and electronics. Some examples of watt usage include:

  • Lightbulbs – A standard 60W incandescent lightbulb uses 60 watts. LED and CFL bulbs use less watts for the same brightness.
  • Television sets – Old tube TVs used 100-300 watts depending on the screen size. Modern flatscreen LCD and plasma TVs use 30-150 watts.
  • Computers – Desktop computers use 60-700 watts depending on the components. Laptops use 15-60 watts.
  • Microwave ovens – Microwave ovens use between 500-1500 watts of power for cooking.
  • Hair dryers – A 1200-1500 watt hair dryer is standard for fast drying.
  • Toasters – Most 2-slice toasters use between 800-1500 watts.
  • Electric kettles – 1500-3000 watt kettles are commonly used to boil water.

As you can see, common household appliances and electronics have a wide range of power demands measured in watts. More powerful devices require more watts to operate. When comparing products, looking at the wattage can give you an idea of the energy efficiency and electricity costs.

Kilowatt Usage

Kilowatts are commonly used to measure the power output and consumption of large machinery, generators, and power plants. For example:

  • The world’s largest gas turbine generators can produce over 500 megawatts of power, equivalent to over 500,000 kilowatts.
  • Large commercial jet engines on airliners generate 15,000 to 90,000 kilowatts of thrust power during takeoff.
  • A diesel locomotive’s engine outputs between 2,500 to 5,000 kilowatts to pull freight trains.
  • Nuclear power plants generate electricity in the range of 500 to 1,500 megawatts, or 500,000 to 1.5 million kilowatts.
  • Large cargo ships use enormous diesel engines that produce between 10,000 to 80,000 kilowatts of power.

By comparing these examples, we can see that kilowatts are a common rating used for large-scale power generation and consumption. Machinery and equipment like power plant turbines, jet engines, train locomotives, ships, and generators are often rated by their kilowatt output because the amounts of power are so large.

Watt to Kilowatt Conversion

Converting between watts and kilowatts is straightforward since a kilowatt is equal to 1,000 watts. To convert watts to kilowatts, simply divide the number of watts by 1,000. For example:

3,500 watts / 1,000 = 3.5 kilowatts

To convert kilowatts back to watts, multiply the number of kilowatts by 1,000. For example:

5 kilowatts x 1,000 = 5,000 watts

Some other example conversions:

  • 10,000 watts = 10 kilowatts
  • 1,500,000 watts = 1,500 kilowatts
  • 0.5 kilowatts = 500 watts

As shown, converting between watts and kilowatts simply involves shifting the decimal place three spots left or right, depending on which unit you are converting to. This straightforward conversion allows for easy calculation of power levels between the two units.


In summary, a watt is a unit of power that measures the rate of energy use, conversion, or transfer, while a kilowatt refers to 1,000 watts. Although they measure the same thing, their numerical values differ by a factor of 1,000. Understanding the relationship between watts and kilowatts is important for comparing power usage across different scales and contexts. While watts are useful for measuring small amounts of power, kilowatts allow us to easily discuss the large amounts of power used in homes, businesses, and infrastructure. Whether you’re looking at your lightbulb’s power rating or your monthly electricity bill, recognizing the scale of watts vs. kilowatts helps put power usage into perspective.

The key points to remember are:

  • A watt measures the rate of energy use or transfer.
  • A kilowatt is equal to 1,000 watts.
  • Kilowatts are useful for measuring large-scale power usage.
  • Watts and kilowatts allow us to compare power consumption across different contexts.

Understanding the relationship between these two units is essential for quantifying and comparing power usage across vastly different scales – from small electronics to massive power plants.

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