How Much Does It Cost to Run an AC Per Month in 2026?

Cooling is one of the biggest summer expenses in most American homes, but the actual cost to run an AC per month varies enormously depending on where you live and what you own. This guide shows you how to estimate your own number, what drives it up or down, and how much a more efficient system could save.

The simple formula

You can approximate an air conditioner’s power draw with one line of math: BTU divided by SEER equals watts. A 3 ton system is 36,000 BTU, so a 14 SEER unit draws about 2,570 watts, or 2.57 kilowatts, while running. Multiply that by the hours it runs each day and by your electricity rate, and you have your daily cost. Multiply by 30 for a monthly figure.

Rather than doing it by hand, plug your system size, efficiency, run hours, and state into our cooling cost calculator for a monthly and seasonal estimate.

Why your bill differs from your neighbor’s

Three factors dominate. First, your electricity rate: at around 12 cents per kilowatt-hour in a low-cost state, running an AC is far cheaper than at nearly 30 cents in California or the Northeast. Second, run time: a home in Texas or Florida may run its system twice as many hours as one in the upper Midwest. Third, efficiency: a higher SEER2 unit does the same cooling for fewer watts.

Typical monthly ranges

For a mid-size home running a 3 ton system about 8 hours a day during the cooling season, monthly costs commonly land somewhere between roughly $60 and $200, with hot, high-rate states at the top of that range and mild, low-rate states at the bottom. Your exact figure depends on the three factors above, which is why a state-specific estimate is more useful than a national average. The U.S. Energy Information Administration publishes the residential electricity rates that drive these numbers.

How to lower your cooling cost

Beyond raising the thermostat a few degrees and sealing leaks, the biggest lever is efficiency. Upgrading from an aging 10 to 13 SEER unit to a modern high-SEER2 system can cut cooling power use by a third or more. To see whether that upgrade pays for itself in your climate, use the SEER2 savings calculator. If your system is near the end of its life anyway, estimate a replacement with the AC replacement cost calculator.

Two worked examples

Consider the same 3 ton, 14 SEER system running 8 hours a day. In a lower-cost state at about 13 cents per kilowatt-hour, the unit draws roughly 2.57 kilowatts, uses about 20.6 kilowatt-hours a day, and costs close to $2.70 a day, or around $80 a month. Move that identical system to a high-rate state near 28 cents per kilowatt-hour and the same usage costs about $5.75 a day, or roughly $170 a month. The equipment is the same; only the electricity rate changed. Now swap in an 18 SEER2 unit in that high-rate state and the daily draw drops to about 2 kilowatts, trimming the monthly bill by a meaningful margin over the season.

Behavior that moves the number

Small habits add up over a cooling season. Setting the thermostat a few degrees higher when you are away, using ceiling fans so you feel comfortable at a higher setpoint, keeping blinds closed on sun-facing windows, and changing a dirty filter all reduce run time, which is the multiplier in every cost formula above. None of these replace a right-sized, efficient system, but together they can shave a noticeable slice off each month’s bill without any equipment change.

Estimate your own number

National averages only get you so far, because your bill is set by your specific rate, run hours, and equipment. The fastest way to a realistic figure is to enter your own details into the cooling cost calculator, which applies your state’s electricity rate automatically. If the number surprises you, that is usually a sign your system is either oversized, aging, or running far more hours than it should, each of which points to a different fix worth exploring before next summer.

Frequently asked questions

How much does it cost to run a 3 ton AC per month?

For a 3 ton system running about 8 hours a day, monthly cost commonly ranges from roughly $60 in low-rate states to $200 in high-rate states. Efficiency and run time change the figure.

Does a higher SEER2 lower my monthly bill?

Yes. A higher SEER2 unit uses fewer watts for the same cooling, which lowers the monthly running cost, especially in hot climates with high electricity rates.

What uses the most electricity in an AC?

The compressor. Its power draw is set by the system’s tonnage and efficiency, which is why size and SEER2 rating drive your monthly cost.