Cost to run air conditioning in New Hampshire
A 2.5-ton central unit costs about
$0.57an hour · $124 a year
That is 2,098 watts while the compressor runs, at 27.33¢ a kilowatt hour — New Hampshire's current residential rate.
Across a year
Electricity used
453 kWh
Full-load hours
216
New Hampshire runs only about 500 cooling degree days a year, so an air conditioner here spends most of its life switched off. That is why the annual figure is small even where electricity is not cheap — you are paying for very few hours. At that rate cooling is roughly 6% of a typical New Hampshire household's yearly electricity spend.
What actually changes this
Floor area and efficiency move this figure more than habits do. A home twice this size costs roughly twice as much to cool, and a unit at SEER2 20 instead of 14.3 uses about a third less. The thermostat matters least of the three — each degree cooler adds a few percent, not a multiple.
Common questions
How much does it cost to run AC for an hour in New Hampshire?
About $0.57 an hour for a 2.5-ton central unit drawing roughly 2,098 watts, at New Hampshire's residential electricity price of 27.33¢ per kilowatt hour.
What does air conditioning cost per summer in New Hampshire?
Roughly $124 a year for a 1,800 square foot home, which is about 453 kilowatt hours. New Hampshire runs around 500 cooling degree days a year.
Is it cheaper to leave the AC on all day or turn it off?
Turning it off while the house is empty is cheaper. An air conditioner works against the temperature difference between inside and outside, so a warmer empty house loses less heat gain than a cool one, and the extra cost of cooling back down is smaller than the saving.
Work it out for your home
These figures describe a 1,800 square foot home with a minimum-efficiency unit. Yours is not that home.
Electricity price from the US Energy Information Administration, residential sector, 2026-05. Cooling load estimated from New Hampshire's cooling degree days with an adjustment for humidity. An estimate, not a bill — insulation, ductwork, shading and how long anyone is home all move it.