How much does a Window Air Conditioning Unit Cost per Month?

Want to know how much a window air conditioner will cost each month?

If you’re reading this article, chances are you either:

  1. Own a window air conditioner but are wary of running it too high or too often, or
  2. Are considering purchasing a window air conditioner, but you want to understand how this handy new addition to your home will affect your monthly bills

Either way, you’re in the right place!

In this guide, you’ll learn:

  1. What to know about your window air conditioner to determine how much it costs to run each month
  2. The easy way to estimate how much your air conditioner will cost you each, hour, week or month
  3. What to consider when purchasing a new air conditioner, and
  4. Much more!

With the average energy bills for US families each year exceeding $2,000, it’s a good idea to understand how much your window air conditioner will cost you to run.

Fortunately, we think you’ll see that window air conditioners can be cheap and effective!

What you need to know about how much it costs to run a window air conditioner:

Most electric companies charge for electricity at a fixed rate, expressed as cents per kilowatt-hour (kilowatt-hour is usually expressed as “kWh”). This is the first thing you’ll need to know how much your air conditioner costs.

Aren’t sure how much your electric company charges? Don’t worry! We’ll show you how to find out exactly how much they charge below (we’ll also show you the average in each state).

The other piece of information you need is how much energy your air conditioner uses. The number you need for this is the wattage of the window air conditioner.

In an ideal world, the wattage of the air conditioning unit would always be easy to find, right on the product label. Unfortunately, that isn’t always the case.

You’re more likely to find the number of British Thermal Units (“BTU”) your window air conditioning unit can produce. BTUs aren’t the best for estimating wattage, because different window air conditioners use different amount of power to produce the same BTUs (some window air conditioners are more energy efficient than others – more on that below).

What you’ll need to determine the monthly cost of your window air conditioner

  1. A recent electric bill – This will tell you what your electricity costs, in kilowatt-hours. If you don’t have a recent electric bill handy, don’t worry! We help you estimate it below.
  2. Your air conditioner – You’ll need to check the product label on the unit itself to determine how much energy it uses.
  3. An idea of how often you plan to run the air conditioner
  4. A basic calculator (any calculator you find online will do the trick)

Step 1 – Determine how much you pay for electricity

The most accurate way to do this is to pull up your most recent electric bill and look for what your electric company charges.

If you’re unable to locate your most recent electric bill, and are okay working with an estimate, you can check this link from the U.S. Energy Information Administration for average costs for each of the 50 states. If you’re calculating the cost of a window air conditioner for your home, you’ll want the “residential” column.

Step 2 – Determine the wattage of your air conditioning unit

Check the product label on your air conditioner. Look for the section titled “Electrical” or something similar. If the wattage is listed there, great! Take note of that number.

If not, you have two other options. First, if you have the owner’s manual handy, the wattage will be listed in there. If you don’t have the owner’s manual, check the product label again for the unit’s model number. A quick Google search of the model number will bring up your specific air conditioning unit, and you can find the wattage information online.

Step 3 – Think about how often your air conditioning is on

Take a minute to think honestly about how many hours you run your air conditioner each day.

Do you run it all day, until it cools down at night (8-9 hours)? Do you use it to cool down a bedroom while you’re asleep (7-8 hours)? Do you remember to turn off the air conditioner when you leave the room, or do you tend to let it run?

It’s important to be honest with yourself in this step to avoid a surprise down the road.

Step 4 – Calculate your hourly cost

Once you have your kWh and your air conditioning unit’s wattage handy, you’re ready to calculate the hourly cost. The first thing to do is divide your unit’s wattage by 1,000 (to determine how many kilowatts the unit uses. The air conditioner shown above is a 515-watt unit, so it uses 515/1000 = 0.515 kilowatts.

Next, multiply your kilowatts by the number of hours you will run your air conditioner each day.

If we assume the above air conditioner will run for 8 hours per day, that’s 0.515 * 8 = 4.12 kWh.

Then, multiply that by the ¢/kWh from your electric bill or an estimate from the link above.

If we take the April 2020 average ¢/kWh for the state of New York from the link (17.33¢), we get 4.12kWh * 17.33¢/kWh = 71.40 cents. This means running this particular air conditioner for 8 hours a day (for one day) would add $0.71 to our electric bill. If we do that every day for 1 month (30 days), we see that that running the A/C unit would cost $0.71 * 30 = ~$21.30 on our electric bill.

Note, in actuality this number will be slightly higher due to taxes on the electricity.

Factors that Change the cost of running window Air Conditioners

1. Outside temperature

If you’re trying to keep your bedroom at 75 degrees when it’s 75 degrees out, that’s easy on your air conditioner and won’t require much electricity (which means it’s cheap for you).

However, if it’s 90 degrees outside and you want your room at 70 degrees, that takes much more power from your air conditioner, so will run up your electric bill.

2. BTUs of the Air Conditioner

We talked briefly about BTUs above, and if you checked your air conditioner’s product label you likely saw what we meant. BTUs represent the cooling output of your air conditioner.

The higher the BTUs on your unit, the better job it can do at keeping you cool, but at a higher cost.

3. Energy Efficiency of the Air Conditioner

BTUs aren’t the end of the story, though. Remember above where we said that two window air conditioners can produce the same BTUs at different wattages? The reason why comes down to how energy efficient the air conditioner is. The efficiency of the unit is expressed by the Energy Efficiency Ratio (or EER).

The EER is the ratio of BTUs the unit can product to watts it uses (so units that can produce more BTUs with fewer watts earn a higher EER).

EER is expressed as a number, usually between 6 and 12. The average EER for a window air conditioner is around 8.5, so any unit at above 8.5 is easier on your electric bill.

4. Size of the room

If your window air conditioner is set up in a small bedroom, it will be much easier (and cheaper) to cool than if it’s trying to cool an entire floor of your home. This is mainly what that BTU number is used for. Check out this table from to get an idea of how many BTUs are needed for your room.

We hope this guide helped you understand how much your window air conditioner costs to run each month. Thanks for reading!

Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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