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

About $20.01 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 34.74¢/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?

California has the 2nd 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 California (June 2026 rates)

At 34.74¢ per kilowatt-hour — California's average residential price in June 2026 — running a window air conditioner costs $240 a year. That is 89% more than the national average of $127. California's residential rate is up 3.4% from June 2025, which moves this appliance from $232 to $240 a year.

Per hour: 25.0¢
Per day of use: $2.00
Per month: $20.01
Per year: $240

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 California compares

California pays 34.74¢/kWh, the 2nd most expensive residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $113 more a year than the typical U.S. household pays for the same use. Running the same window air conditioner costs $90.62 a year in Nevada and $364 in Hawaii, so where you live changes this bill by $274 a year.

State	Rate	Per month	Per year
New York	29.49¢	$16.99	$204
Maine	29.59¢	$17.04	$205
Massachusetts	29.61¢	$17.06	$205
California	34.74¢	$20.01	$240
Hawaii	52.72¢	$30.37	$364

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

What else costs about the same in California

Electric clothes dryer$271 a year in CA Aquarium$205 a year in CA Gaming pc$203 a year in CA

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 California?: About $20.01 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 34.74¢/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?: California has the 2nd most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $127 a year.