How Much Does a Window AC Unit Cost to Run?

Read this article to learn how to calculate how much a window AC unit costs to run, what factors impact its efficiency, and ways in which you can save in costs.

If you’re thinking about buying a window AC unit, but you’re on a budget and don’t know if you’ll be able to afford your electricity bill at the end of the month, in this article, we will address how much a window AC costs to run. Air conditioners have become a very popular and important home appliance that many people, especially those who live in a hot and dry climate, want and need. And, much like any other energy-linked appliance you purchase, there are tips and tricks to use a window air conditioner efficiently and be able to save on your electricity bill. So keep on reading to learn how to calculate how much your window air conditioner may spend hourly, daily, or monthly, and what you can do to lower the price of that bill.

How Much Does It Cost to Run a Window Air Conditioner?

Using a window air conditioner is more energy-efficient than purchasing a portable air conditioner. The cost of running it will depend on a few factors, which we will break down later on. Below you will find two tables indicating the average cost of running a window air conditioner per hour and per month based on the BTU (British Thermal Unit) of the window AC, which is the measurement used to show how much energy your AC uses to remove the hot air from your home per hour.

Here’s how much it would cost to run a window AC unit per hour based on the BTU of the air conditioner:

Average cost per hourBTU of window AC unit
$0.195 per hour15,000 BTU window air conditioner
$0.143 per hour12,000 BTU window air conditioner
$0.117 per hour10,000 BTU window air conditioner
$0.085 per hour8,000 BTU window air conditioner
$0.065 per hour5,000 BTU window air conditioner

Here’s how much it would cost to run a window AC unit per month based on the BTU of the air conditioner:

Average cost per monthBTU of window AC unit
$46.80 per month15,000 BTU window air conditioner
$33.60 per month12,000 BTU window air conditioner
$26.40 per month10,000 BTU window air conditioner
$20.40 per month8,000 BTU window air conditioner
$15.60 per month5,000 BTU window air conditioner

How to Calculate Your Cost of Running a Window AC?


Calculating the cost of running your window AC unit is not difficult and you won’t need a professional’s help to find the answer. All you need is three simple numbers to add to an equation and you’ll have your cost. Here are the numbers you need to calculate the cost of running a window AC unit:

  • The watt usage of the window air conditioner (you can easily find it in the AC specifications)
  • How much you pay per kilowatt/hour (you can find that out by looking at one of your electricity bills or on the electricity company’s website)
  • The number of hours you want to run the window AC unit per day

After you get all three numbers, all you need to do is follow this very simple formula in order to obtain the cost:

Watts of AC unit x 1 hour usage ÷ 1000 x number of how much you pay kilowatt/hour = cost of running hourly

If you want to find out the daily cost of running your window AC unit, follow this short formula, which is based on an 8-hour use per day:

Cost of running hourly x 8 hours per day = daily cost of running 

Factors That Impact the Cost of Running a Window AC


Besides the number of BTU and watt requirements of a window AC unit, there are some other factors that could raise the cost of running a window unit at the end of each month. Let’s elaborate on them!

Indoor and outdoor temperatures

If you want to purchase a window air conditioner and run it every day, chances are that you live in a place where the climate is hot and dry. If that is the case, then you should know that when the air outside is way too hot, the air conditioner will have to spend a lot more energy than usual in order to cool your home. 

Similarly, the lower you set the temperature of your AC, the more and harder it will have to work to reach that temperature and start the fan mode to maintain it. This is why it is always recommended not to set a very low temperature and rather one that is just comfortable enough.


Another important factor to consider is how well insulated your home is. Regardless of how it is,  open doors or windows in the area where the AC is running will make it work a lot harder and spend more energy to cool your house because of all the hot air coming in. So when you turn on your air conditioner, make sure that you don’t have any windows or doors open that will allow the outside air to sneak its way into the cool, conditioned air.

Cooling capacity

One of the most important factors that affects the cost of running a window AC unit is its capacity to cool an area. The higher its cooling capacity, the more energy it will use and the higher the cost of running it. The cooling capacity of an air conditioner is measured in BTU (British Thermal Unit). The higher the BTU number, the larger the space it can cool. See the table below for reference.

BTU number of window air conditionerThe square feet 
14,000 BTU700 square feet 
12,000 BTU550 square feet 
10,000 BTU450 square feet 
9,000 BTU400 square feet 
8,000 BTU350 square feet 
5,000 BTU150 square feet 

As we have already established, a window AC unit that has 14,000 BTU, for example, will be more powerful in its capacity to cool an area and therefore be more costly to run. This means that it would not be cost-efficient for you to buy this window AC unit if the space you want to cool is about 500 square feet. 

Energy efficiency 

And lastly, energy efficiency is another very important factor that will definitely impact the cost of running a window air conditioner. As with the BTU, the same goes for energy efficiency. A unit that has a higher count of Energy Efficient Ratio (EER) or Combined Energy Efficient Ratio (CEER) will be more efficient, making it also more expensive to run. You can find out the EER or CEER of your window AC unit on a sticker on it.

How to Make the Most of Your Window AC


If you already own a window AC unit and want to learn some helpful tips to make the most out of it, we are providing you with four easy and effective tips to use your air conditioner more efficiently and to even increase its lifespan. 

Increase the temperature

The first instinct we may have when turning on our window AC unit is to set it at the lowest temperature in order to cool faster. What you could do instead is to set it at the highest temperature you’re comfortable to save energy and money. Increasing the temperature by 10 or 15 degrees Fahrenheit can save you up to 10% of air conditioning costs per year.

Change filters

Because the AC unit will take outside air and cool it down for you before releasing it into your lovely home, it means that particles in the air like dust, debris, and pollen can and will gather in your AC unit’s filters. This is why it’s important to regularly check, clean, and change them when necessary to increase the air conditioner’s lifespan and keep it running smoothly and efficiently.


As we mentioned above, insulating your house when you turn on your AC will save you a lot of money and energy. It’s wasteful to leave the air conditioner on while you open doors and windows to let air in. This will make the unit work harder and spend more energy than needed. So for a better, more affordable experience, remember to close all doors and windows when you turn on your air conditioning! 

Leave it running when leaving the house briefly

One thing that many people can mistake for energy efficiency is turning off the AC unit when leaving the house briefly. If you turn off the AC unit and then turn it back on not long after, this will definitely spend more energy because when you set the temperature for the second time it will work hard to jumpstart and reach that set temperature. However, if you leave it on when stepping out of the house briefly, that is definitely more energy efficient. 

The Bottom Line

If you’ve learned at least one new thing after reading this article, then we’ve done our job. What is your next step then? Running your window AC unit doesn’t have to be very costly if you follow the tips outlined in this article, and if you do so, not only you will save yourself some money but also be doing less damage to the environment–clearly a win-win situation. 

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