Watt Vs. Kilowatt: What’s the Difference?

Here’s what we’ll cover in this guide:

• What is a watt?
• What is a kilowatt?
• How to convert watts to kilowatts
• What is the difference between kilowatts and kilowatt-hours?
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What Is the Difference Between Watts and Kilowatts?

What Is a Watt?

A watt (W) is a unit of power equivalent to one joule per second. In this context, power refers to the rate at which work is performed or energy is transferred. You can think of power as “the ability to do work,” whether that work is generating electricity or consuming it.

The most common places where you might see watts used as a descriptor would be basic appliances such as lightbulbs, dishwashers, TVs or dryers. This measurement refers to the power of a specific device. You can find the power ratings of your appliances in the technical specifications, user manuals or on the labels.

For example, you might see a 100-watt lightbulb or a 1,500 W dishwasher. This means that the lightbulb only has the ability to transfer (in this case consume) 100 W in a given moment. The dishwasher can consume 1,500 W at a time.

An easy way to conceptualize this is by thinking of a faucet or hose. Power, or wattage, would reflect the pressure of the hose rather than how much water actually comes out of it. Our 100 W lightbulb would have very low water pressure.

You rarely encounter units of energy smaller than watts in your daily life. From there, you can scale up to the following:

• Kilowatts (1,000 watts)
• Megawatts (1,000,000 watts)
• Gigawatts (1,000,000,000 watts)

What Is a Kilowatt?

Just like watts, a kilowatt (kW) measures the power of an electrical device or appliance. A kilowatt is equal to 1,000 W. Watts are relatively small units of power, so it’s common to see larger-scale measurements using kW and beyond.

For example, when talking about the power needed for one lightbulb, you would use watts. If you’re talking about the power of an array of 40 solar panels, kW serves as a much more practical measurement that avoids too many zeros getting in the way. You’ve likely seen solar systems measured in kW since it’s much easier to describe a system as 10 kW than 10,000 watts.

For example, 40 solar panels (at 350 W each) would make an array totalling 14,000 W (40 x 350 W = 14,000 W). Isn’t it easier to call it 14 kW?

Even further, if you are discussing the power of a solar farm, commercial solar project or large power plant, megawatts might be the best measurement to do so. For context, the largest solar farms in the world clock in around 2 gigawatts (GW).1

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How to Convert Watts Into Larger Power Measurements

Luckily, the conversion between watts, kW, MW and GW is fairly simple. You can quickly convert the number of watts (W) to kilowatts (kW) by dividing your wattage by 1,000.

 Watts Kilowatts 1,000 W 1 kW 10,000 W 10 kW 100,000 W 100 kW

You can quickly convert kilowatts (kW) to megawatts (MW) by dividing the kilowatts by 1,000.

 Kilowatts Megawatts 1,000 kW 1 MW 10,000 kW 10 MW 100,000 kW 100 MW

You guessed it — you can then convert megawatts (MW) to gigawatts (GW) by dividing the megawatts by 1,000. 1,000 MW = 1 GW.

 Megawatts Gigawatts 1,000 MW 1 GW 10,000 MW 10 GW 100,000 MW 100 GW

What Is a Kilowatt-Hour (kWh)?

While watts (W) and kilowatts (kW) are measurements of power, kilowatt-hours (kWh) are units of electrical energy.

The most important distinction between kW and kWh is that a kilowatt-hour of energy reflects the total amount of electricity used over a period of time. Kilowatts, as we’ve mentioned, refer instead to the rate at which a device can generate or consume electrical power.

To continue with our hose analogy — kW refers to the potential water pressure of a hose. Kilowatt-hours would measure the amount of water used by a hose over time. The greater the power (or kW), the more water it will use over an hour.

More specifically, a kilowatt-hour measures the energy consumed by a 1,000-watt (W) or 1 kilowatt (kW) electrical appliance operating for one hour. The higher the wattage, the more kWh the appliance has to consume to stay powered over time.

Here’s a simple example. If you were to keep a 100 W TV turned on for a full hour, it will have consumed 100 watt-hours (Wh), or 0.1 kWh. Let’s look at a few other common appliances and how many kWh of energy they consume over an hour.

Here’s the equation: (W / 1,000 kW) x 1 hour.

• 100 W lightbulb = 0.1 kWh in an hour
• 1,000 W space heater = 1 kWh in an hour
• 1,500 W dishwasher = 1.5 kWh in an hour
• 2,000 W air conditioner = 2 kWh in an hour

What about 10 hours? The equation would be (W / 1,000 kW) x 10 hours

• 100 W lightbulb = 1 kWh in 10 hours
• 1,000 W space heater = 10 kWh in 10 hours
• 1,500 W dishwasher = 15 kWh in 10 hours
• 2,000 W air conditioner = 20 kWh in 10 hours

Starting to make sense?

Kilowatt-hours (kWh) follow the same conversion patterns as watts and kilowatts. These include:

• Watt-hours (Wh)
• Megawatt-hours (MWh)
• Gigawatt-hours (GWh)

Why Do Watts (W), Kilowatts (kW) and Kilowatt-Hours (kWh) Matter?

Let’s get down to the dollars and cents — why does it matter? Well, your electricity bill will reflect how many kWh of electricity your home consumed over the month. Your utility company or electricity provider will have a rate that it charges per kWh.

The average home’s power consumption lands around 900 kWh of electricity per month, depending on the season. If your electricity rate is 13 cents per kWh (about standard), then the average energy bill will land around \$117 (that’s 900 kWh x \$0.13)

If you’re looking to conserve energy, it can be helpful to understand which of your appliances consumes the largest amount of energy. That can help you prioritize which appliances to conserve the use of or to upgrade to energy-efficient models.

For example, did you know dryers can use up to 5,000 W? Let’s do the math on how much that energy usage would cost you per month if you run your dryer for an hour per day.

5,000 W dryer = 5 kWh in an hour

5 kWh x 30 days = 150 kWh

150 kWh x \$0.13 = \$20 per month

\$20 x 12 months = \$240 per year

Does \$240 a year in energy costs make a big difference in your budget? Then consider investing in a drying rack or energy-efficient dryer.

Understanding the role of W, kW and kWh is what empowers homeowners to make decisions like these that can reduce their total electricity usage.

Article author
Expert reviewer
Karsten is an editor and energy specialist focused on environmental, social and cultural development. His work has been shared by sources including NPR, the World Economic Forum, Marketwatch and the SEIA, and he is certified in ESG with the CFA Institute. Before joining EcoWatch, Karsten worked in the solar energy sector, studying energy policy, climate tech and environmental education. A lover of music and the outdoors, Karsten might be found rock climbing, canoeing or writing songs when away from the workplace.

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