Home › Appliances › Window air conditioner

How much does it cost to run a window air conditioner?

At the U.S. average residential price of 18.34¢ per kilowatt-hour (June 2026), running a window air conditioner costs about $127 a year. Your own bill depends on your state's rate, which ranges from 13.11¢ to 52.72¢ across the country.

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.

Cost by state

Same appliance, same usage, 51 different prices. Sorted cheapest first.

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 many watts does a window air conditioner use?

About 900 W while running, though it cycles on and off, so average draw is 720 W.

How much does a window air conditioner cost per month?

About $10.56 a month at the U.S. average rate, or $127 a year.

Where is it cheapest to run?

Nevada, at $90.62 a year, versus $364 in Hawaii — a spread of $274.