How much does a window air conditioner cost per month in South Carolina?

About $8.91 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 15.47¢/kWh.

How many kilowatt-hours does a window air conditioner use?

Roughly 691 kWh a year under these assumptions, or 0.72 kWh for every hour it runs.

Is that expensive compared with other states?

South Carolina has the 20th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $127 a year.

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Cost to run a window air conditioner in South Carolina (July 2026 rates)

At 15.47¢ per kilowatt-hour — South Carolina's average residential price in July 2026 — running a window air conditioner costs $107 a year. That is 16% less than the national average of $127. South Carolina's residential rate is up 5.2% from July 2025, which moves this appliance from $102 to $107 a year.

Per hour: 11.1¢
Per day of use: 89.1¢
Per month: $8.91
Per year: $107

Assumption: 900 W at a 80% duty cycle, 8 hours a day, 120 days a year — 691 kWh a year. Typical of a 10,000 BTU window unit. Small 5,000 BTU units draw closer to 500 W; 15,000 BTU units closer to 1,400 W. Use the calculator to swap in the numbers from your own model.

How South Carolina compares

South Carolina pays 15.47¢/kWh, the 20th cheapest residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $19.63 less a year than the typical U.S. household pays for the same use. Running the same window air conditioner costs $87.92 a year in Louisiana and $332 in Hawaii, so where you live changes this bill by $244 a year.

State	Rate	Per month	Per year
South Dakota	15.37¢	$8.85	$106
Arizona	15.38¢	$8.86	$106
South Carolina	15.47¢	$8.91	$107
West Virginia	15.78¢	$9.09	$109
Texas	15.88¢	$9.15	$110

States ranked by average residential price, cheapest first. See all 51 states for a window air conditioner.

What else costs about the same in South Carolina

Electric clothes dryer$121 a year in SC Aquarium$91.47 a year in SC Gaming pc$90.34 a year in SC

Cutting the number down

Sealing the gaps around the sleeve with foam matters more than the unit's efficiency rating. Warm air leaking back in is load you pay to remove twice.
An inverter model modulates instead of slamming on and off, which shows up as a lower effective duty cycle rather than a lower nameplate watt.
Shading the outdoor half of the unit lowers the temperature it rejects heat into, which lowers the work it has to do.

Questions

How much does a window air conditioner cost per month in South Carolina?: About $8.91 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 15.47¢/kWh.
How many kilowatt-hours does a window air conditioner use?: Roughly 691 kWh a year under these assumptions, or 0.72 kWh for every hour it runs.
Is that expensive compared with other states?: South Carolina has the 20th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $127 a year.