How to Calculate Residential Air Conditioning Costs

Find the price per kilowatt hour that your utility company charges you. This will be printed somewhere on your utility bill, and in most cases will be around 10 cents per kilowatt hour or less.

Locate the air conditioner's draw in wattage, On almost all appliances, this number will be printed or etched on the air conditioner with a "W" next to it; the number indicates the wattage that the appliance uses in one hour. If there is no wattage value printed on the air conditioner, you can use an ammeter -- available at electronics and hardware stores -- to determine the air conditioner's current then multiply it by either 120 or 240, depending on whether it uses a 120- or a 240-volt power cord.

Calculate the cost of the air conditioner by multiplying the wattage value by the number of hours that you typically run the system in a day. Take the result and multiply it by the cost per kilowatt hour that your utility company charges you and you will arrive at an estimation in dollars of how much money it costs to run the air conditioner in a typical day. Further multiplication can yield estimations for weekly, monthly and yearly costs as well.