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

About $8.73 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 15.15¢/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 Dakota has the 17th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $126 a year.

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Cost to run a window air conditioner in South Dakota (August 2026 rates)

At 15.15¢ per kilowatt-hour — South Dakota's average residential price in August 2026 — running a window air conditioner costs $105 a year. That is 17% less than the national average of $126. South Dakota's residential rate is up 9.0% from August 2025, which moves this appliance from $96.08 to $105 a year.

Per hour: 10.9¢
Per day of use: 87.3¢
Per month: $8.73
Per year: $105

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 Dakota compares

South Dakota pays 15.15¢/kWh, the 17th cheapest residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $20.81 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 Nevada and $326 in Hawaii, so where you live changes this bill by $238 a year.

State	Rate	Per month	Per year
Florida	14.99¢	$8.63	$104
Arizona	15.05¢	$8.67	$104
South Dakota	15.15¢	$8.73	$105
Kansas	15.47¢	$8.91	$107
Montana	15.57¢	$8.97	$108

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 Dakota

Electric clothes dryer$118 a year in SD Aquarium$89.58 a year in SD Gaming pc$88.48 a year in SD

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 Dakota?: About $8.73 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 15.15¢/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 Dakota has the 17th cheapest average residential rate in the country, so this appliance costs less here than the U.S. average of $126 a year.