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

About $10.64 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 18.48¢/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?

Delaware has the 19th most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $127 a year.

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

At 18.48¢ per kilowatt-hour — Delaware's average residential price in July 2026 — running a window air conditioner costs $128 a year. That is about the same as the national average. Delaware's residential rate is up 11.5% from July 2025, which moves this appliance from $115 to $128 a year.

Per hour: 13.3¢
Per day of use: $1.06
Per month: $10.64
Per year: $128

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 Delaware compares

Delaware pays 18.48¢/kWh, the 19th most expensive residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $1.18 more 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
Minnesota	17.45¢	$10.05	$121
Virginia	17.55¢	$10.11	$121
Delaware	18.48¢	$10.64	$128
Wisconsin	19.06¢	$10.98	$132
Illinois	19.22¢	$11.07	$133

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

What else costs about the same in Delaware

Electric clothes dryer$144 a year in DE Aquarium$109 a year in DE Gaming pc$108 a year in DE

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 Delaware?: About $10.64 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 18.48¢/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?: Delaware has the 19th most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $127 a year.