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How To Calculate Your Electric Bill

Updated: 02/22/2021

Whether you want to calculate your total electricity bill, see what’s eating up the most energy in your home or find out how much energy a specific appliance consumes, this guide has a method you can use.

Calculating Your Total Electricity Bill Cost

You can calculate your total electricity bill cost by multiplying the number of kilowatt-hours you consumed by your electricity rate.

How your electricity bill is calculated

A kilowatt-hour is a measurement of how much electricity you use and your electricity rate is how much you’re charged for each kilowatt-hour. You can find all this information on your electricity bill.

However, your bill only tells you your total usage, not what that total usage is comprised of. If you want that information, you will have to follow one of three methods:

  1. Manually Calculate Your Electricity Bill
  2. Use Household Averages
  3. Purchase A Monitoring Device

How To Calculate Your Electric Bill Manually

To calculate your electricity bill manually, you will need to find how many kilowatt-hours each electric appliance consumes and add them together. You can do this by following four steps:

  1. Find the electric appliance’s wattage and estimated monthly use in hours
  2. Multiply the appliance’s wattage and estimated monthly use to find watt-hours consumed
  3. Divide watt-hours consumed by 1,000 to find the appliance’s total kilowatt-hours consumed
  4. Add the monthly electricity consumption of all your appliances together to find your total electricity usage.

Manually calculating your electricity bill takes more time, but it allows you to determine how much each electrical appliance in your home contributes to your electricity bill without spending money on a monitoring device. 

Example Of Manually Calculating Your Electric Bill

If you want to use this method with all or multiple electrical appliances, make a list on a sheet of paper. Divide that list into three sections: Electrical Appliance, Appliance Wattage, and Estimated Monthly Use (in hours). This will help you keep track of all the information you need.

Here’s an example:

A table to help you calculate your monthly energy bill

1. Find the electric appliance’s wattage and estimated monthly use in hours

The first thing that we need to do is find the wattage and estimated monthly use of every electrical appliance you want to measure. 

The wattage of the product is often labeled on the back of the product itself. It should look like this:

Showing how you can find wattage on an appliance

If it is not labeled on the product, you can look at the original package or user manual to find the wattage. 

If you cannot find the wattage from the two methods above, you can find an average wattage for the product online. However, this will likely not be accurate, so we suggest you purchase a cheap energy monitor. 

A cheap energy monitor will run you about $20-$30 on Amazon and take care of the calculations for you. For instance, this electricity usage monitor will not only tell you the wattage of the product but it will also tell you how many kWh the electrical product uses.

If you do not want to perform any calculations, a simple energy monitor is the way to go.

Unless you are using a simple energy monitor, your estimated monthly electricity use of a device or appliance is just a best guess. If you don’t have one, write that best guess down. Ensure that your estimated monthly use is in hours or the calculations will not work.

After you determine your estimated monthly use and the product wattage of all the appliances you are measuring, you have everything you need to make your calculations.

2. Calculate how much electricity an appliance consumes

To find how much electricity an electric appliance consumes in kilowatt-hours in a month, use these two formulas in the order they appear:

  • Appliance Wattage × Estimated Monthly Use (in hours) = Watt-hours
  • Watt-hours / 1,000 = Kilowatt-hours (kWh)
Table with formulas for calculation monthly electricity usage

For our example, we will first find the watt-hours of a product. 

In our example, we will be using a 135-watt television, that has an estimated monthly use of 30 hours.

To find the watt-hours used, we will use the first formula: Watt-hours = Appliance Wattage * Estimated Monthly Use (in hours)

135 watts * 30 hours = 4,050 watt-hours

Table with formula for calculating watt-hours

Next, we must convert that into kilowatt-hours (kWh). This is because kWh is the unit of measurement for our electricity bills. 

To transfer watt-hours into kilowatt-hours, we use the second formula: Kilowatt-hours = Watt-hours/1,000
4050 watt-hours / 1,000 = 4.05 kilowatt-hours

Table with formula for calculating kilowatt-hours

Our 135-watt television used for 30 hours a month comes out to 4.05 kilowatt-hours a month.

Repeat these steps as needed to determine the power usage of all your devices and appliance products.

3. Calculating Total Kilowatt-Hours Consumed

The second step was the hardest part! You may even be done if you only wanted to track the kWh consumption of one or two products.

However, if you measured all of your electrical appliances, you have one last step. 

Find the sum of your kWh usage, by adding all of the product’s kWh usage together. 

This should give you a number that is relatively close to the kWh usage on your bill. And if you multiply your total kWh usage by your electricity rate (your electricity rate is also found on your bill), you should get a number close to the amount you paid on your electricity bill.

A quick note about heating and air conditioning. It can be hard to get an accurate measure of your estimated monthly usage of heating and A/C. If you have a smart thermostat, it can tell you how long it operates each month. If not, you can get an idea of the air conditioning’s/heating’s kWh usage by taking the sum of all other electrical appliances kWh usage, and then subtracting that sum from the total energy consumption listed on your bill. 

Use Household Averages

If you don’t want to spend the time manually calculating your electricity bill and just want a general idea of how much electricity each of your electrical appliances consumes, you can use household averages. 

These are the averages according to Energy Star:

  • Heating: 29%
  • Cooling: 17%
  • Water Heating: 14%
  • Lighting: 12%
  • Other: 11%
  • Electronics: 4%
Chart with breakdown of home energy use by percentage.

However, this does not reflect your specific usage. If you want the specifics of what’s consuming the most energy in your home, you will need to either manually calculate your bill or purchase a monitoring device. What you choose depends on how much time you want to put into it and how much money you want to spend. 

Purchase a Monitoring Device

If you don’t mind spending some money and want accurate readings quickly, purchase an electricity monitoring device.

There are multiple devices for home energy monitoring out there, but the one with the best ratings (as of January 2021) is the Sense Energy Monitor. This device is installed directly into your electrical panel and records how much energy specific devices are consuming in real-time. 

The only downside to this method is that this device costs $300. There are similar monitors that are less expensive, but according to the reviews, these sensors are not as accurate and have a whole host of other issues.

You could also get an inexpensive $20 monitor to measure how much electricity a specific device or appliance uses. We recommend this method to make it easier for you to manually calculate your monthly electricity bill as well.

You Now Have Everything You Need To Calculate Your Electricity Bill

You can use this page to find out how much energy each electric appliance uses and then use that information to see what you can cut back on to lower your electricity bill.

However, there is only so much electricity usage that you can cut. So if you want to save money on your electricity bill, learn about switching electricity suppliers here on ElectricityRates.com. Switching electricity suppliers can help you save up to 30% on your electricity bill and you don’t even have to change your energy use!