Understanding Your Energy Usage

Learn how to calculate power consumption by kWh per month.

Written by Dominique Sabins

Edited by Aviva Hauser

Last updated January 30, 2025

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Key Points

  • Calculating your power consumption can help you lower your electricity usage and save on energy bills.
  • You can estimate your monthly energy usage using the formulas listed on this page.
  • Learn about our experts’ tips on how to lower your home’s energy usage.

Calculate your household energy usage

Understanding how to calculate energy consumption can help you lower your electricity usage and monthly bills. Every device or appliance in your home uses electricity, measured in kilowatt-hours (kWh). Your power consumption level is the total kWh used in your home.

Your energy provider charges you for every kWh of electricity you use every month. The best way to lower your energy bill is to find ways to decrease the electricity you consume. By tracking your household’s energy usage, you can learn about what affects your total consumption and find opportunities to cut down your electricity usage.

Formula to calculate your home electricity cost

How to calculate power consumption in your home

Your monthly energy bill accounts for how much electricity you use to power your appliances, electronic devices, HVAC system, lights, and more. You can check your past electric bills to estimate your typical energy usage.

You can manually estimate your energy usage by looking at which appliances and devices use the most power in your home and calculating their overall cost to use. The costs associated with heating, cooling, and lights can be harder to manage since they’re running most of the time, but it’s easy to find out how much your additional devices add to your total power consumption. Once you’ve done that, you can adjust your usage — and lower your bill — by unplugging those devices or using them less often. To manually calculate your power consumption, use the following steps:

  1. Calculate the watts your devices and appliances use per day.
  2. Add up the total amount of watts.
  3. Convert the watts to kilowatts. There are 1,000 watts in one kilowatt.
  4. Estimate the cost by multiplying monthly kilowatts by your electric rate.

Finding the wattage of a device

Most devices have a label listing the number of watts they use. The wattage label can be found on the device (usually on the bottom or back) or in the owner’s manual.

If you can’t find the wattage label, there are a few other ways to locate this information:

  • Purchase a wattage measuring device which displays the wattage of a device when you plug it in.
  • Contact the manufacturer with your device’s model number.
  • Look up your device and model number online. Most manufacturers list the wattage of their products on their websites.

We’ve also provided a list that shows the average wattage of common household devices. Though the wattage of your particular device may vary, this can give you a rough estimate.

Coffee Maker900-1200 watts
Toaster 800-1400 watts
Iron100-1800 watts
Ceiling fan 65-175 watts
Space heater (40gal) 4500-5500 watts
Hair dryer1200-1875 watts
Laptop 50 watts
Computer monitor 150 watts
Computer tower 120 watts
Television 19"-36" 65-133 watts
Television 53"-61" 170 watts

How to calculate kWh per month

The following sections outline how to calculate your home’s monthly kWh usage, including an example to demonstrate how your monthly kWh usage contributes to your overall energy bill.

Calculate daily watt-hours

To calculate your energy consumption, multiply an appliance’s wattage by the number of hours you use it in a day (the watt-hours).

Device Wattage (watts) X Hours Used Per Day = Watt-hours (Wh) per day

Example: A 170-watt television used three hours per day

170 watts X 3 hours = 510 Wh/Day

Converting watt-hours to kilowatts

Your electricity bill is measured in kilowatt-hours (kWh), not watt-hours. One kilowatt is equal to 1,000 watts. To calculate how many kWh a device uses, divide the watt-hours from the previous step by 1,000.

Device Usage (Wh) / 1,000 (Wh/kWh) = Device Usage in kWh

Example: A television using 510 Wh of electricity per day

510 / 1,000 = 0.51

How to find monthly energy usage

Now that we know how many kWh the appliance uses per day, we can estimate that usage over the course of a month. Multiply the daily usage by 30 days to calculate the approximate monthly kWh usage.

Daily Usage (kWh) X 30 (Days) = Approximate Monthly Usage (kWh/Month)

Example: A television using 0.51 kWh of electricity per day

0.51 kWh X 30 Days = 15.3 kWh/Month

In this example, a 170-watt television you use for three hours every day accounts for 15.3 kWh of energy per month. This is the television’s monthly energy consumption. The next section will cover how that translates to your electricity bill.

How much do appliances cost on my electricity bill?

To estimate how much an appliance adds to your electricity bill, check your latest bill to find the price you pay per kWh, otherwise known as your electric rate. To determine how much your appliances cost per month, multiply your electric rate by the estimated monthly usage from the previous step.

Monthly Usage (kWh) X Electric Rate ($/kWh) = Approximate Cost per Month

Example: A television using 15.3 kWh/Month with an electric rate of 16 cents per kWh ($0.16/kWh)

15.3 kWh X $0.16 = $2.44/Monthly Bill

This television would cost $2.44 per monthly energy bill based on these calculations. While that might not seem like much, the appliances and devices in your home can add up quickly.

Remember, your appliances and devices only account for part of your energy bill. Your bill also includes heating, cooling, and lighting, which add to your costs. If your home has a smart meter, you can track your usage and multiply the kWh for that month by your electric rate (like we did in the most recent step) to get a more accurate bill estimate.

The following table shows the categories that consume the most energy in the average home, according to the Energy Information Administration (EIA).

CategoryPercentage of Energy Usage
Space cooling16.2%
Space heating15.9%
Water heating11.4%
Refrigerators and freezers6.9%
Lighting4.4%
Televisions3.5%
Computers2.3%
All other devices and appliances39.4%

Calculating your energy bill comes down to knowing your usage and the price you pay for energy. Our energy experts recommend a fixed-rate energy plan for predictable energy bills. Since your rate remains the same under a fixed-rate plan, you can budget more easily for your energy costs. Enter your ZIP code on this page to explore available fixed-rate options.

Directions on how to calculate your appliances monthly kWh energy usage

Seasonal energy trends

There are certain times of the year when you will likely use more energy, and your bill will increase as a result. For most people, this comes during summer and winter, when extreme temperatures require you to rely on air conditioning or heating. Taking steps to lower energy consumption and increase energy efficiency during high-usage periods can help lower electricity bills.

Here are a few energy consumption tips from our experts to help you save electricity in your home and potentially lower your energy bill:

  • In the winter, the most energy-efficient temperature for your thermostat is 68 degrees Fahrenheit. In the summer, set it to 78 degrees. Whenever you’re away from home, you should lower or raise your thermostat’s setting so you aren’t paying to heat or cool an empty house.

  • Using a smart thermostat instead of a manual or programmable thermostat can help you manage your HVAC unit and lower bills. Smart technology lets you remotely increase or decrease temperatures in your home from your smartphone.

  • Lower the temperature on your water heater to 120 degrees Fahrenheit. That will reduce your home’s electricity usage while also slowing buildup and corrosion in your home’s water heater and pipes.

  • ENERGY STAR-certified appliances consume less electricity than non-certified models. For example, ENERGY STAR washers and dryers use 20% less energy than other models. Swap out old, outdated appliances for these energy-efficient units. You can also search for energy-efficient electronics such as TVs, computers, and game consoles. Switching these devices to the “power-saving” mode will help decrease the amount of electricity they use.

  • LED light bulbs use 75% less energy than traditional incandescent lighting and have a lifespan up to 25 times longer. Switching to LEDs is a low-cost way to make your lighting more efficient.

Energy usage FAQs

  • The Energy Information Administration (EIA) found that air conditioning, space heating, and water heating were the top sources of electricity consumption in residential U.S. homes. Together, these three categories account for 43.5% of energy usage. If you’re looking for ways to decrease your home’s energy consumption, consider cutting back on heating and cooling if it is comfortable.

  • One way to lower your energy usage is to decrease how often electronics and appliances are running in your home. Start by turning off lights and unplugging electronics while they’re not in use. This includes computers, game consoles, toasters, and more. You can also decrease how often you heat and cool your home. Try setting your thermostat to 78 degrees in the summer and 68 degrees in the winter.

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