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Air Conditioner Electricity Cost Calculator

Central air conditioning is the single biggest driver of summer electricity bills in most homes, often accounting for half the bill in hot months. A typical 3-ton central AC draws around 3,500 watts while running, but like a refrigerator it cycles on and off to hold your set temperature — so the real cost depends heavily on how hard it has to work. This calculator lets you set the run time and see what your AC actually costs per hour, day, and cooling season.

Appliance
Wattage(W)
Quantity
Usage measured in
Usage
Duty cycle (share of time actually drawing power) 45%
State (auto-fills rate)
kWh / day
12.60kWh

watts × hours × duty ÷ 1000

Cost / month
$64.26

at your state rate

Cost / year
$782

this appliance

Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.

Build a whole-home estimate item by item.

Understanding your AC electricity bill

Central AC wattage varies by size: a 2-ton unit draws roughly 2,000–2,400 W; a 3-ton about 3,000–3,600 W; a 5-ton up to 6,000 W. But the compressor doesn't run continuously — it cycles based on thermostat demand. In moderate weather, duty cycles of 30–40% are typical; on the hottest days, the system may run at 80–100%.

AC efficiency is rated as SEER (Seasonal Energy Efficiency Ratio). A 14 SEER system uses 30% more electricity than an equivalent 20 SEER unit to deliver the same cooling. If your system is over 15 years old and rated below 14 SEER, replacement with a modern high-efficiency unit or heat pump can cut cooling costs by 20–40%.

For the best accuracy, find your unit's rated tonnage on the nameplate and divide by 0.8 to estimate compressor watts (a rough rule is 1 kW per ton for efficient modern systems, 1.2–1.5 kW per ton for older ones).

Frequently asked questions

A typical 3-ton central AC cycling about 45% of the time uses roughly 38 kWh a day, or about $6.50 at the U.S. average rate — but in a heat wave with the system running nearly constantly, daily cost can easily double.

Because it moves a large amount of heat and runs for many hours a day in hot weather. Cooling is energy-intensive, and unlike lighting or electronics, an AC can draw several thousand watts for hours at a stretch — which is why summer bills often run 50% or more above spring.

Yes, meaningfully. Each degree higher on the thermostat reduces run time, and because the AC is such a large load, even 2–3 degrees can cut cooling costs noticeably over a month. Setting it higher when you're away captures most of the savings with no comfort loss.

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