How Much Does an AC Cost Per Month

Days are again growing longer and hotter and the temptation to leave your air conditioner on all day is high. When summer days roll around, you can expect the energy bills to spike as the sweet relief provided by your AC unit comes with a cost.

It’s hard to put a price on comfort, but if you are watching your spending, you might want to estimate how much your heating and cooling costs you per month & try some clever tricks to reduce the electricity cost of air conditioner.

How Much Does it Cost to Run an Air Conditioner

Before we start calculating the air conditioner cost, we should do a quick overview of the energy units that we will be using.

  • BTUs – A BTU stands for British Thermal Unit. It is used to measure the amount of energy that is required for your air conditioner to cool one pound of water by one degree Fahrenheit. Your air conditioner might have this number expressed in tons (on the energy label). One ton equals 12,000 BTUs per hour. The term one ton comes from how much heat is required to melt a block of ice that weighs one ton.
  • Ampere – Amperage, or AMP, is a measure of how much electricity is flowing through an electric circuit per unit of time.
  • Watt – A Watt (W) is another unit of power, and is defined as one Joule of energy per second. Since watt is actually very small, we can convert 1000 watts to a kilowatt (kWh)
  • Kilowatt Hour – Kilowatt-hours measure the number of kilowatts used by an appliance in the duration of one hour.
  • Volt – A Volt is a measure of the electric potential between two points on a wire. In the United States, the standard power outlet voltage is 120 V.

If you are still confused, we don’t blame you. Electricity is a difficult concept to grasp because we can’t see it. Let’s instead borrow an analogy that we all can relate to more easily – a flow of water. The rate at which the water flows is measured as a current (in Amperes). As the water flows through a pipe, it creates pressure against the pipe, which would be the voltage (measured in volts). And wattage is the amount of water (power) is released each second (measured in watts).

Navigating energy conversions can go a long way towards a better understanding of your utility bills and ultimately – being able to reduce them. If you are curious about other energy units and how to estimate your monthly electric bill, you can read our simple guide to help you master the basics.

But back to air conditioners…

AC Cost Factors

Now that the understand the energy conversions involved, we can continue with our estimation of how much does it cost to run an air conditioner for a period of time. There are different factors that will impact your air conditioning electricity cost:


Energy costs

The biggest impact on your final energy bill will be the price you pay per kWh of electricity. The average electric rates that residents pay are different in every US state, from the cheapest Louisiana (7.71 cents per kilowatt-hour) to the most expensive Hawaii at whooping 29.18 cents per kilowatt-hour.

However, ff you are fortunate to live in one of the 18 energy-deregulated U.S. states, you have the choice to switch electricity suppliers and lock in a cheaper fixed-rate for a duration of a contract (12, 24, or even 36 months).


AC energy efficiency

The more efficient your air conditioner, the less power it burns through to cool your home. A room air conditioner's efficiency is measured by the energy efficiency ratio (EER). To calculate your AC EER, you have to divide your air conditioner's capacity (in BTUs) by its power (in watts). This number will most likely be provided on the data plaque mounted to the side fo your AC (like on the picture below).

If you can't find it, you can follow this simple step-by-step guide to determine how efficient is your AC. What's a good energy efficiency ration? As a rule of thumb, you want your EER to be 9 or higher. If you have the choice, invest in an Energy Star certified AC units, that are 15 to 50% more efficient than the non-certified alternatives.


Thermostat settings

How you program your thermostat will have a great impact on how much it costs you at the end of the month. Rather than programming it manually (and forgetting to turn it off when you leave the house), you should pre-program your air conditioner to come up with the most efficient schedule.
Alternatively, you can invest in a smart thermostat that will learn your living habits and re-program your AC automatically to fit your needs. You don't have to spend a fortune on them. Some electricity suppliers offer free gadgets, such as Google Nest Hub, or a complimentary programmable thermostat when you sign up for an energy plan.


Outdoor conditions

During extremely hot and humid summers, your air conditioner will probably have to work harder and longer than usual to keep your home cool, which will likely be reflected in your electric bill. Although the outside temperature isn't something that you can control, it is important to be aware of it as we are approaching a particularly hot summer.


AC installation, maintenance, and ducts

If your air conditioner wasn't installed properly, it may not work as efficiently. Also, you should have the AC filters, coils, and fins professionally maintained on a regular basis, especially after a few years of consistent use. Some energy suppliers offer A/C bundle plans together with their power plans, including the air conditioning maintenance cost together with a fixed-rate electricity plan for a better price.

Formula For Determining AC Costs To Operate

So now that we have all the ingredients, we can finally calculate how much does air conditioning cost per month. However, keep in mind that the below calculations are based on many assumptions and should be used solely as guidance.

Step 1: Let’s start by assuming that you have a standard 4-Ton Air Conditioner (Read where to find the tonnage of your unit here). Next, calculate how many amps does your unit draw:

  • 2-Ton Air Conditioner – 15 amps
  • 3-Ton Air Conditioner – 18 amps
  • 4-Ton Air Conditioner – 21 amps

Step 2: Remember, amperes indicate the rate at which the water flows (in our earlier analogy). The next step is to determine the amount of water itself – wattage. To figure this out, simply multiply the amperage from step 1 by the voltage of your outlet – let’s assume it’s a standard 220V.

21 amps x 220 V = 4620 watts or 4.62 kilowatts. What does that mean? If you let your air conditioner run for one hour, it will burn 4.62 kilowatts of energy.

Step 3: The last step in calculating your air conditioning costs is multiplying the 4.62 kilowatts by however many hours will your AC be running. If maths isn’t your thing, don’t worry. The Washington State University’s Energy Program offers a free air conditioning running costs calculator on their website.

One last thing – Your price per kWh will greatly affect your AC system cost to run. For example, if you live in Texas and you haven’t yet switched energy suppliers, you are probably paying the standard energy tariff of 11.85 cents per kWh. However, a quick look at offers from other providers returns several long term contracts with rates between 5.99 and 10 cents. With an average household usage of approximately 1000 kilowatts a month, this can make a huge difference to your utility bills.

Price to Run AC

Now, let’s add up the number of hours per day usage to get the total estimate of your electricity cost for air conditioner in your monthly utility bill.

Cost To Run AC For An Hour – From the earlier section, we know that your AC system uses 4.62 kilowatt-hours of energy (based on approximate figures!). Multiply this number by your rate per kWh to get the actual cost of one hour’s use of your HVAC unit. From the earlier example again, let’s say your current rate is ¢ 11.85 per kWh.

4.6 kWh x ¢ 11.85 = 54.51 cents

This is how much it costs to run your AC system for an hour.

Cost To Run AC All Night- Let’s say that the summer day turned into a hot night and opening your window to let the breeze in won’t cut it. Do you want to know how much it costs to run your air conditioning unit all night? If your HVAC unit runs for 8 hours in total, these are the costs:

54.51 cents x 8 hours = $4.36

Cost To Run AC All Day – What about if you keep your central air running for the whole day – 24 hours per day in total?

54.51 cents x 24 hours = $13.08 – The cost to run the HVAC system all day.

The above numbers confirm that air conditioners are not a cheap affair. The U.S. Energy Information Administration (EIA) ‘s estimate is that heating and cooling account for about 12% of U.S. home utility costs. These costs may be higher if your home HVAC unit is old (over 5 years), less efficient (not an Energy STAR rated model), or if you are paying a higher rate per kilowatt of electricity.


Below are answers to some of the questions you might have about your air conditioner cost:

How much does your utility bill go up with an air conditioner?

EIA estimates that central air conditioning cost accounts for about 12% of U.S. home utility costs. The final number, however, will depend on different factors, including the efficiency of your unit, your thermostat settings, the outside temperature, and your electricity costs per kilowatt hour.

How much does AC cost per hour?

To calculate how much electricity does a AC use per hour, you first need to convert the tonnage of your unit into amperes, based on the below guide:

  • 2-Ton Air Conditioner – 15 amps
  • 3-Ton Air Conditioner – 18 amps
  • 4-Ton Air Conditioner – 21 amps

Then, multiply the amps by the voltage of your outlet (220V is the standard) to get the wattage of your unit (W used per hour). Finally, multiply the number by your current electricity rate to find your hourly HVAC cost to run. You can use the free cost of running air conditioner calculator resource online if you would like or follow our comprehensive guide to determine the cost to run.

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