Kilowatt-hour (kWh) is a measurement of energy that electric companies use to determine your electric consumption. Because the power company uses kWh, you can clearly see your consumption on your electricity bills. You can use this calculation to see how much power you use in a year and then try to reduce your consumption in the future. If you have not been in your house for more than a year, you can estimate your annual kWh usage by prorating.
If You've Lived in the House a Year or More
Find your power bills for the past year. If you do not have physical copies of your bills, most electric companies have them available online.
Write out the kWh used for all 12 months in the preceding year. For example, assume your kWh were 200, 223, 212, 232, 243, 263, 233, 211, 230, 270, 210, 204.
Add together each month's kWh. In the example, your annual usage equals 2,731 kWh.
If You've Lived in the House Less Than a Year
Pull together all the electric bills you have.
Add together the kWh for the months you've been in the house. For example, assume you have three months of statements that show kWh of 120, 80 and 100 for a total of 300 kWh.
Multiply your kWh by 12. Divide the result by the number of months for which you have bills. In the example, 300 times 12 equals 3,600; 3,600 divided by 3 equals 1,200. This represents the number of kWh you will use in a year if your consumption habits stay the same.