How Much Does It Cost to Run an Air Conditioner? A 2026 Cost Breakdown

July 14, 2026 · Appliance Guides · 9 min read

Air conditioning is the single largest driver of summer electricity bills in most of the United States. In hot-climate states, cooling can account for more than half of a household's electricity use during July and August. Understanding what your air conditioner costs to run, hour by hour and month by month, is the first step to keeping your summer bills under control. This guide breaks down the running costs of every common type of air conditioner and shows you how to cool your home for less.

The quick answer: a typical central air conditioner uses about 3,000 to 3,500 watts while running, costing roughly 55 to 65 cents per hour at the national average rate of 18.56¢/kWh. A medium window unit costs about 18 cents per hour. Over a hot month, central AC commonly adds $100 to $250 to an electric bill.

How Air Conditioner Cost Is Calculated

Air conditioners are rated in two ways: by wattage (how much electricity they draw) and by BTU (British Thermal Units, a measure of cooling capacity). To estimate running cost, you need the wattage, which you can find on the unit's label or calculate from the BTU rating and efficiency (EER or SEER).

One nuance: air conditioners do not run at full power continuously. A properly sized unit cycles on and off to maintain your set temperature, typically running 50–70% of the time on a hot day. So a central AC rated at 3,200 watts might average closer to 2,000–2,200 watts of actual draw over a full afternoon.

Running Cost by Air Conditioner Type

The table below compares typical running costs at the national average rate, based on the average power draw for each AC type running continuously.

AC Type	Typical Watts	Cost/Hour	Cost/Month*
Small window unit (5,000 BTU)	450 W	$0.08	$20
Medium window unit (10,000 BTU)	1,000 W	$0.19	$45
Portable AC (12,000 BTU)	1,300 W	$0.24	$58
Central AC (3 ton)	3,200 W	$0.59	$142
Ductless mini-split	1,200 W	$0.22	$53

*Monthly estimate assumes 8 hours of actual compressor runtime per day for 30 days.

What Makes One AC Cheaper Than Another: SEER Rating

The efficiency of an air conditioner is measured by its SEER (Seasonal Energy Efficiency Ratio). A higher SEER means the unit produces more cooling per kilowatt-hour. Older units from the early 2000s often have SEER ratings around 8–10, while modern units range from 14 to 22 or higher. Upgrading from a SEER 9 unit to a SEER 18 unit can roughly halve your cooling electricity cost for the same comfort.

If your central AC is more than 12–15 years old, its declining efficiency and refrigerant leaks may be quietly inflating your summer bills. While a new system is a significant investment, the energy savings, combined with available rebates and tax credits, can shorten the payback period considerably in hot climates.

Twelve Ways to Cut Your Air Conditioning Costs

1. Raise your thermostat. Each degree higher can cut cooling costs by roughly 3%. Setting the thermostat to 78°F instead of 72°F can save 15–18%.
2. Use a programmable or smart thermostat. Let the house warm up while you are away and cool down before you return. See our guide on smart thermostat savings.
3. Run ceiling fans. Fans make you feel 4°F cooler for a fraction of the cost, letting you raise the thermostat.
4. Close blinds and curtains during the hottest part of the day to block solar heat gain.
5. Change your air filter monthly. A clogged filter forces the system to work harder and run longer.
6. Seal ducts and gaps. Leaky ducts in attics can waste 20–30% of cooled air.
7. Service your unit annually. Low refrigerant, dirty coils, and worn parts all reduce efficiency.
8. Cool only occupied rooms with window units or a mini-split instead of running central AC for an empty house.
9. Shift heavy appliance use (oven, dryer) to cooler evening hours so the AC does not fight added heat.
10. Add attic insulation to keep heat from radiating down into living spaces.
11. Use a whole-house or attic fan in the evening to flush hot air and reduce AC runtime.
12. Consider a time-of-use rate plan and pre-cool your home before peak pricing hits. Learn how in our time-of-use rates guide.

Window Unit vs Central AC: Which Is Cheaper?

For cooling a single room, a window unit is far cheaper to run than central air, because you are only cooling the space you occupy. For a whole house, central AC is more convenient and often more efficient per square foot, but it cools every room whether or not you are using it. Many households save money by using central AC sparingly and relying on a window unit or mini-split in the bedroom overnight.

The right choice depends on your home layout and how many rooms you actually use. A single person in a large house often wastes money running central AC and would do better with zone cooling. A family that uses the whole home benefits from central air's even coverage.

Humidity and the "Feels Like" Factor

Air conditioners do two jobs: they lower temperature and remove humidity. In humid regions, the dehumidifying effect is a big part of comfort. Running your AC on a slightly higher temperature with good humidity control often feels more comfortable than blasting cold air, and it uses less energy. A properly sized unit that runs longer cycles removes humidity better than an oversized unit that short-cycles, which is why bigger is not always better when replacing a system.

Understanding SEER Ratings and Efficiency

When you compare central air conditioners or mini-splits, the key efficiency number is the SEER rating (Seasonal Energy Efficiency Ratio). The higher the SEER, the less electricity the unit uses to deliver the same cooling. Older systems installed in the 1990s and early 2000s often carry SEER ratings of 8–10, while modern units start around SEER 14 and high-efficiency models reach SEER 20 or more. Upgrading from a SEER 9 system to a SEER 16 unit can cut cooling energy use by roughly 40%, which in a hot climate with a large summer bill can mean several hundred dollars saved each year.

That said, a new high-SEER system is a major purchase, so the payback depends on how much you cool and how expensive your electricity is. If your current unit is over 15 years old, struggles to keep up on hot days, or needs frequent repairs, replacement usually makes both comfort and financial sense. If it is only a few years old, you will get more value from sealing ducts, adding insulation, and using smarter scheduling than from an early replacement.

The Bottom Line

Running an air conditioner costs anywhere from 8 cents an hour for a small window unit to 60 cents an hour for central air, and cooling can easily become the largest line item on your summer electric bill. The most effective ways to cut the cost are raising your thermostat a few degrees, using fans and smart scheduling, and keeping your system well maintained. Estimate your own cooling costs with our Seasonal Electric Cost Calculator and see how AC fits into your total bill with the Monthly Electric Bill Calculator. For a complete summer strategy, read our guide on lowering your electric bill in summer.

Frequently Asked Questions

How much does it cost to run central air conditioning per month?

A typical 3-ton central air conditioner draws about 3,200 watts and costs roughly 59 cents per hour at the national average rate. Assuming about eight hours of actual compressor runtime per day, that works out to around $142 a month. In very hot climates with longer runtimes, central AC can add $200 to $250 or more to a summer bill, making it the largest single line item during peak cooling months.

Is it cheaper to run a window unit or central air?

For cooling a single room, a window unit is far cheaper because you only cool the space you occupy; a medium window unit costs about 19 cents per hour versus 59 cents for central air. For a whole house, central AC is more convenient and often more efficient per square foot, but it cools every room whether occupied or not. Many households save by using central air sparingly and relying on a window unit or mini-split in the bedroom overnight.

What temperature should I set my AC to save money?

Setting your thermostat to 78 degrees Fahrenheit when you are home is the commonly recommended balance of comfort and savings. Each degree lower can raise cooling costs by roughly 3 percent, so cooling to 72 instead of 78 can increase your bill by 15 to 18 percent. Using ceiling fans lets you feel about 4 degrees cooler, so you can raise the thermostat without losing comfort.

Does a higher SEER air conditioner really save money?

Yes, especially in hot climates. SEER measures cooling produced per kilowatt-hour, so a higher number means lower running cost. Upgrading from an old SEER 9 unit to a modern SEER 18 model can roughly halve your cooling electricity use for the same comfort. If your central AC is more than 12 to 15 years old, its declining efficiency and possible refrigerant leaks may be quietly inflating your summer bills.

Why is my air conditioner making my electric bill so high?

Air conditioning is the biggest summer energy user in most homes, often more than half of the July and August bill. High costs can come from an oversized or aging unit, dirty filters or coils, leaky ducts wasting cooled air, poor insulation, low refrigerant, or simply setting the thermostat very low. Regular maintenance, sealing ducts, raising the thermostat a few degrees, and using fans are the most effective ways to bring the cost down.

How much does it cost to run a window air conditioner for a month?

A medium 10,000 BTU window unit drawing about 1,000 watts costs roughly 19 cents an hour, or about $45 a month assuming eight hours of runtime a day at the national average rate. A small 5,000 BTU unit costs about half that, while a large unit costs more. Because a window unit cools only one room, it is far cheaper than central air for spot cooling a bedroom or home office.

Should I leave my AC on all day or turn it off when I leave?

For most homes, letting the temperature rise while you are away and cooling down when you return saves energy, which is exactly what a programmable or smart thermostat automates. The old belief that it costs more to 're-cool' a house is largely a myth; the energy saved during the warmer hours outweighs the extra runtime on return. In very humid climates, some people prefer a modest setback rather than fully off to keep humidity in check.