The calculator below will calculate the amount of electricity, in wattage, that is used to operate different types of AC units. To get started, select the AC unit you own from the dropdown menu, select the appropriate daily usage and then your cost per KW/H.
- Type of AC Unit: Select the type of air conditioner that is appropriate for your situation.
- Average Daily Use: Currently set at 3 hours per day on average based on 12 hours used during the 3 summer months and zero the rest of the months. Please adjust this accordingly based on where you live and how much you will run the AC unit for.
- KW/H Price: Currently set at an average of $0.136 per kilowatt hour, which is the US average. Please refer to the current prices in your area for the most accurate cost estimation. The full list of KW/H prices by state can be found below the calculator.
KW/H Prices by State
Find your state in the list below and use the most accurate KW/H price in the calculator.
District of Columbia
How Much Power Does my AC Use?
The amount of power (watts) used by your air conditioner will be based on the size of it (BTU) and the efficiency of the unit (EER). BTU stands for British Thermal Units and is a common way AC units are sized. EER stands for Energy Efficiency Ratio, which is a score assigned to units based on how efficient they are. The higher the score the better.
Now that the definitions are out of the way, we can use these two units (BTU and EER) to determine the estimated wattage use of your AC unit.
The formula is as follows: BTU / EER = Wattage
A Quick Example
Your air conditioner is a 12,000 BTU window unit that has an EER rating of 9.5. To find the required wattage you would do the following:
Wattage Requirements for Common AC Sizes
Below are some of the more common single room AC unit sizes in BTUs and their watts required to power them. We are using an average of 9.5 EER for these examples.
AC Size (in BTUs)
Yearly Cost ($.136 KW/h)
AC Unit Types vs. Watts
The type of AC unit will determine the range of watts that will be required to power it. This is due to some ac unit types being more efficient and other types, such as central AC, cool a much larger space which requires more power.
There are two main categories for AC units:
- Central Air Conditioning
- Single Room Units
The most important thing to know here is that central AC units cool your entire home. This requires a lot of power to do this which is why the amount of watts will be higher compared to single room units.
Single Room Units
Single room units are used to only cool one room. This requires much less power since you are cooling a smaller space. Some examples of single room units include window air conditioners and portable air conditioners.