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Air Conditioner Cost Calculator
See what your air conditioner costs to run per hour, per month and over a full summer. Choose your type of unit or enter its wattage directly.
Typical values. Newer, high-efficiency units use less.
The compressor shuts off once the room is cool, which cuts real usage.
19¢ is roughly the 2026 U.S. average. Your bill lists your actual rate.
How much does it cost to run an AC per hour?
Here is what common air conditioners cost at the 2026 U.S. average of about 19¢ per kWh, assuming the compressor runs the whole time. Real costs are usually lower because units cycle off once the room cools.
| Unit | Per hour | 8 hrs/day for a month |
|---|---|---|
| Window, 5,000 BTU (450 W) | $0.09 | $20.52 |
| Window, 8,000 BTU (700 W) | $0.13 | $31.92 |
| Window, 12,000 BTU (1,050 W) | $0.20 | $47.88 |
| Portable, 10,000 BTU (1,100 W) | $0.21 | $50.16 |
| Central, 3 ton (3,000 W) | $0.57 | $136.80 |
How the cost is calculated
The tricky part with AC is that the power draw changes. The compressor uses most of the electricity, and it shuts off once the room hits the thermostat setting. On a mild day it might run a third of the time. During a heat wave it might never stop. The "how hard is it working" setting accounts for that.
Ways to lower your AC costs
- Raise the thermostat a few degrees. Each degree warmer means the compressor runs less often.
- Turn it up when you leave. Cooling an empty home all day costs more than cooling it back down when you return.
- Block the sun. Closing blinds on sunny windows keeps a lot of heat out in the first place.
- Use a fan with it. A ceiling fan uses around 60 W compared to 1,000 W or more for AC, and moving air makes a room feel cooler at a higher setting.
- Clean the filter. A clogged filter makes the unit work harder for the same cooling.
- Pick a window unit over portable when you can. Portable units are usually less efficient because the hot parts sit inside the room.
Frequently asked questions
How much does it cost to run a window AC unit?
A typical window unit draws 450 to 1,100 watts depending on size. At about 19¢ per kWh, that's roughly 9¢ to 21¢ per hour of compressor run time, or about $20 to $50 a month running 8 hours a day.
Is it cheaper to leave the AC on all day?
Usually not. Letting the temperature rise while you're away and cooling it down when you return generally uses less energy than keeping the home cool all day.
Does central air cost more than window units?
Per hour, yes, because central AC cools the whole home. Cooling only the room you're using with a window unit is often cheaper. Cooling an entire house with several window units can cost about the same or more.
How many watts does an air conditioner use?
Small window units use around 450 W, large window units around 1,000 W, and central AC systems roughly 2,000 to 4,000 W depending on size and efficiency.