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

About $27.18 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 47.18¢/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?

Hawaii has the most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $126 a year.

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

At 47.18¢ per kilowatt-hour — Hawaii's average residential price in August 2026 — running a window air conditioner costs $326 a year. That is 160% more than the national average of $126. Hawaii's residential rate is up 22.5% from August 2025, which moves this appliance from $266 to $326 a year.

Per hour: 34.0¢
Per day of use: $2.72
Per month: $27.18
Per year: $326

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 Hawaii compares

Hawaii pays 47.18¢/kWh, the most expensive residential electricity of the 51 U.S. jurisdictions EIA reports. For this appliance that works out to $201 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 Nevada and $326 in Hawaii, so where you live changes this bill by $238 a year.

State	Rate	Per month	Per year
Alaska	29.41¢	$16.94	$203
California	29.75¢	$17.14	$206
Massachusetts	30.48¢	$17.56	$211
Maine	32.11¢	$18.50	$222
Hawaii	47.18¢	$27.18	$326

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

What else costs about the same in Hawaii

Electric clothes dryer$368 a year in HI Aquarium$279 a year in HI Gaming pc$276 a year in HI

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 Hawaii?: About $27.18 a month, assuming 900 W at a 80% duty cycle, 8 hours a day, 120 days a year at 47.18¢/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?: Hawaii has the most expensive average residential rate in the country, so this appliance costs more here than the U.S. average of $126 a year.