kWh Kilowatt hour definition meaning

What Is A Kilowatt-hour (kWh) And What Can It Power?

When most people look at their electric bill, they just glance at the total to see how much they have to pay that month.

Some might look to see if the meter reading matches the one on their meter at home, but very few people look further than that. If this describes you, you’re missing out on an important piece of information about the way you use electricity: the number of kilowatt-hours you use each month.

Knowing what a kilowatt-hour is and what it can power can save you money. This knowledge can help you monitor electricity usage, make educated choices about saving energy, and lower your monthly electric bill. You’ll also learn the formula to convert KW to kWh.

What is a Kilowatt-Hour?

A kilowatt-hour, otherwise known as a kWh, is a way to measure how much energy you’re using.

It’s not the number of kilowatts you’re using in an hour, even though that seems to make sense. A kWh equals the amount of energy you would use by keeping a 1,000 watt appliance running for one hour. In metric, 1,000 = kilo, so 1,000 watts equals a kilowatt.

For instance, if you turned on a 100 watt bulb, it would take 10 hours to use one kilowatt-hour of energy. A 2,000 watt appliance, on the other hand, would only take half an hour. It all comes down to dividing the number of watts in an appliance into 1,000.

Kilowatt-Hour vs. Kilowatt

What’s the difference between kilowatt vs. kilowatt-hour? A kilowatt is 1,000 watts, which is a measure of power. A kilowatt-hour is a measure of the amount of energy a certain machine needs to run for one hour.

So, if you have a 1,000 watt drill, it takes 1,000 watts (or one kW) to make it work. If you run that drill for one hour, you’ll have used up one kilowatt of energy for that hour, or one kWh.

What Can a Kilowatt-Hour Power?

Obviously, every appliance in your home will use a different amount of power. Here are some of the usages for the more (or less) common items in a home:

  • 50″ LED Television: around 0.016 kWh per hour
  • Electric dishwashers: around 2 kWh per load
  • Most ovens are around 2.3 kWh per hour
  • Electric water heater: 380-500 kWh per month
  • Refrigerator (24 cu. ft frost free Energy Star): 54 kWh per month
  • Clothes Washer (warm wash, cold rinse): 2.3 kWh per load
  • Clothes Dryer: 2.5 – 4.0 kWh per load
  • Air Conditioner (3 ton 12 SEER): 3.0 kWh per hour
  • Nissan Leaf Electric Car – 40 kWh per full battery charge
  • Amazon Echo, Telling a Joke – 4 watts per joke (not sure how many hours you want to listen to that…)

The Energy Guide label on newer appliances will include the estimated yearly electricity usage. Multiply that by your rate per kilowatt-hour and you have the cost to use that device.

If you want to know more about the Energy Guide label and what appliances use the most electricity, we have additional resources for you.

How Do I Calculate How Many kWh an Appliance Uses?

Heating and cooling your home use the most electricity, and are around 50% of your bill. But in second place are your appliances, at around 20% of your bill.

You can calculate how much power they use with a simple exercise. This can help you figure our how many kWh your house uses per day and where the power goes.

  • Make a list of major appliances in your home (washing machine, dish washer, refrigerator, television should be on there…)
  • Look for a tag on the appliance that looks like this:label showing watts of a device
  • Write down the number of watts consumed by that appliance
  • In the next column, write down how many hours a day you use that appliance.
  • Now calculate the kWh for each appliance, following this example:

Appliance: Refrigerator

Number of Watts: 300 watts

Hours used per day: 24 hours

300 watts X 24 hours = 7,200 watt-hours per day

7,200 watt-hours per day / 1000 = 7.2 kWh per day

7.2 kWh per day X 30 days in a month = 216 kWh per month

Here’s another example:

Appliance: Dishwasher

Number of Watts:  1200 watts

Hours used per day:  2 hours

1200 watts X 2 hours = 2,400 watt-hours per day

2,400 watt-hours per day / 1000 = 2.4 kWh per day

2.4 kWh per day * 30 days in a month = 72 kWh per month

There are also several online resources and calculators that can help you with this, if you prefer that to pen, paper and calculator!  Or create a spreadsheet to help you on this project.

What Does a kWh of Electricity Cost?

The cost of kWh varies depending on where you live. In deregulated markets, what you pay per kWh can also vary depending on whether you have selected an alternative energy supplier. The US Energy Information Administration (EIA) reports on average prices by state.

Residential customers in Texas, where deregulation has been in place since 2001, pay an average of 11.69 cents per kWh, compared to the national average of 12.87 cents per kWh.

How Many kWh Does a House Use Per Day?

One common question is, how many kWh does a house use per day? The amount of kWh you use will depend on:

  • How big your residence is
  • The age of your home (especially related to insulation)
  • The number of people living there
  • The type, number and age of appliances
  • How you heat or cool your home
  • Whether you have a pool
  • The climate you live in

According to the EIA, in 2017, the average annual electricity consumption for a U.S. residential utility customer was 10,399 kilowatt hours (kWh), an average of 867 kWh per month. That means the average house uses 28.9 kWh in a day (867 kWh / 30 days).

How to See Your Electricity Usage

The easiest way to see how much electricity you use is to simply check your electric bill. Your electricity provider will show the number of kilowatt-hours you use each month. Some have also started to add small charts on your bill so you can see monthly trends and patterns.

In addition, if you have a Smart Meter, your electricity provider probably also provides online tools for you to track your usage. Some also send out weekly status reports to your email to show you how much electricity you have used in the past week and forecast how much you will use in the upcoming week.

If you are interested in reducing your electricity bill, knowing your kWh usage is the first step. Take some time to look at your electric bill and check out your electricity provider’s online tools to monitor your usage. When you’re ready to shop for your next electricity plan, you will be more familiar with your usage patterns and be able to find the perfect electricity plan for your lifestyle.

How to Lower Your Electric Bill

One of the best ways to lower your electricity bill is by being energy-conscious.

It begins by doing simple things like turning off the lights when you leave the room and adjusting your thermostat when you go to work. You can take even more control over your expenses by paying attention to your appliances. Those that are on standby all the time, such as televisions, computers and stereo systems, use power all day long even when they’re not turned on.

In addition, use energy saving appliances every chance you get. When it’s time to buy a new microwave oven or dishwasher, the kWh rating is one of the first details you should check. Look for the yellow ENERGYGUIDE product label to find the energy usage for an appliance and see if it is ENERGY STAR compliant.

If you are in a deregulated electricity market like Texas, Ohio or Connecticut, you can shop for a cheap electricity rate. Your local utility company continues to deliver electricity to your home, respond in the case of a power outage and read your meter. However, your supply can come from a competitive retail energy supplier. This allows you to pick from a fixed rate plan, prepaid electricity, free nights or free weekends, and green energy. Or you can select the cheapest electricity provider in your area.

Read more: 12 Ways to Reduce your Electricity Costs