How much does it cost to run a window air conditioner?
Short answer: A window air conditioner drawing 900 watts costs about $0.16 per hour at the U.S. average residential price of 18.31¢ per kWh. Used 8 hours a day, 30 days a month, that is about $39.55 per month and $474.60 per year. In Louisiana, the cheapest state, the same use costs $27.48 a month; in Hawaii, the most expensive, $103.68.
Window air conditioner cost calculator
Hours the compressor is actually running. On a mild day it may cycle on only half the time; in a heat wave it can run almost continuously.
Energy used: 216.0 kWh per month. Default price is the U.S. residential average; pick your state or type the price from your own bill.
A window air conditioner draws roughly 450 to 1,400 watts while its compressor is running, depending on its size. A typical 10,000 BTU unit sits near 900 watts, which is the default used in the calculator on this page.
Cost by size and setting
Costs below use the U.S. average price and 8 hours a day, 30 days a month.
| Type | Power | Per hour | Per month |
|---|---|---|---|
| 5,000 BTU (small bedroom) | 450 W | $0.08 | $19.77 |
| 8,000 BTU (medium room) | 700 W | $0.13 | $30.76 |
| 12,000 BTU (large room) | 1,100 W | $0.20 | $48.34 |
Why BTUs and efficiency ratings matter
BTU is the cooling capacity; watts is what you pay for. The link between them is the efficiency rating on the yellow EnergyGuide label, shown as CEER. Divide the BTU rating by the CEER to get the approximate running watts. A 10,000 BTU unit with a CEER of 11 draws about 910 watts; an older one with a rating of 9 draws about 1,110 watts for the same cooling.
Inverter models can slow their compressor down instead of switching it fully on and off. They draw far less than their nameplate figure once the room is cool, which is why they cost less to run than the label wattage suggests.
Window unit or central air?
Cooling one bedroom with a window unit at night and letting the rest of the house warm up is almost always cheaper than running a 3,500-watt central system for the whole home. Cooling every room with separate window units usually is not.
How to lower the cost
- Buy the right size. An oversized unit short-cycles, removes less humidity and wastes power.
- Clean the filter monthly in summer. A clogged filter makes the compressor run longer.
- Close the foam side panels and seal gaps around the unit so cooled air stays in.
- Set it to 78°F rather than 72°F when you can; each degree lower adds run time.
Cost to run a window air conditioner in every state
Based on 900 watts for 8 hours a day, 30 days a month, at each state's average residential electricity price for July 2026.
| State | Price per kWh | Per hour | Per month | Per year |
|---|---|---|---|---|
| Alabama | 16.40¢ | $0.15 | $35.42 | $425.09 |
| Alaska | 28.83¢ | $0.26 | $62.27 | $747.27 |
| Arizona | 15.38¢ | $0.14 | $33.22 | $398.65 |
| Arkansas | 14.33¢ | $0.13 | $30.95 | $371.43 |
| California | 33.61¢ | $0.30 | $72.60 | $871.17 |
| Colorado | 17.00¢ | $0.15 | $36.72 | $440.64 |
| Connecticut | 24.16¢ | $0.22 | $52.19 | $626.23 |
| Delaware | 18.48¢ | $0.17 | $39.92 | $479.00 |
| District of Columbia | 25.21¢ | $0.23 | $54.45 | $653.44 |
| Florida | 15.03¢ | $0.14 | $32.46 | $389.58 |
| Georgia | 16.27¢ | $0.15 | $35.14 | $421.72 |
| Hawaii | 48.00¢ | $0.43 | $103.68 | $1,244 |
| Idaho | 13.73¢ | $0.12 | $29.66 | $355.88 |
| Illinois | 19.22¢ | $0.17 | $41.52 | $498.18 |
| Indiana | 16.73¢ | $0.15 | $36.14 | $433.64 |
| Iowa | 15.99¢ | $0.14 | $34.54 | $414.46 |
| Kansas | 15.27¢ | $0.14 | $32.98 | $395.80 |
| Kentucky | 13.81¢ | $0.12 | $29.83 | $357.96 |
| Louisiana | 12.72¢ | $0.11 | $27.48 | $329.70 |
| Maine | 32.41¢ | $0.29 | $70.01 | $840.07 |
| Maryland | 21.41¢ | $0.19 | $46.25 | $554.95 |
| Massachusetts | 30.49¢ | $0.27 | $65.86 | $790.30 |
| Michigan | 23.05¢ | $0.21 | $49.79 | $597.46 |
| Minnesota | 17.45¢ | $0.16 | $37.69 | $452.30 |
| Mississippi | 14.54¢ | $0.13 | $31.41 | $376.88 |
| Missouri | 16.09¢ | $0.14 | $34.75 | $417.05 |
| Montana | 14.99¢ | $0.13 | $32.38 | $388.54 |
| Nebraska | 13.78¢ | $0.12 | $29.76 | $357.18 |
| Nevada | 12.77¢ | $0.11 | $27.58 | $331.00 |
| New Hampshire | 26.60¢ | $0.24 | $57.46 | $689.47 |
| New Jersey | 25.19¢ | $0.23 | $54.41 | $652.92 |
| New Mexico | 16.09¢ | $0.14 | $34.75 | $417.05 |
| New York | 29.90¢ | $0.27 | $64.58 | $775.01 |
| North Carolina | 15.16¢ | $0.14 | $32.75 | $392.95 |
| North Dakota | 13.41¢ | $0.12 | $28.97 | $347.59 |
| Ohio | 19.45¢ | $0.18 | $42.01 | $504.14 |
| Oklahoma | 14.35¢ | $0.13 | $31.00 | $371.95 |
| Oregon | 15.97¢ | $0.14 | $34.50 | $413.94 |
| Pennsylvania | 21.72¢ | $0.20 | $46.92 | $562.98 |
| Rhode Island | 28.29¢ | $0.25 | $61.11 | $733.28 |
| South Carolina | 15.47¢ | $0.14 | $33.42 | $400.98 |
| South Dakota | 15.37¢ | $0.14 | $33.20 | $398.39 |
| Tennessee | 13.71¢ | $0.12 | $29.61 | $355.36 |
| Texas | 15.88¢ | $0.14 | $34.30 | $411.61 |
| Utah | 13.12¢ | $0.12 | $28.34 | $340.07 |
| Vermont | 23.75¢ | $0.21 | $51.30 | $615.60 |
| Virginia | 17.55¢ | $0.16 | $37.91 | $454.90 |
| Washington | 14.71¢ | $0.13 | $31.77 | $381.28 |
| West Virginia | 15.78¢ | $0.14 | $34.08 | $409.02 |
| Wisconsin | 19.06¢ | $0.17 | $41.17 | $494.04 |
| Wyoming | 14.36¢ | $0.13 | $31.02 | $372.21 |
Frequently asked questions
How much does it cost to run a window AC all day?
A 900-watt unit whose compressor runs the full 24 hours uses 21.6 kWh, about $3.95 at the U.S. average price. On most days the compressor cycles, so the real figure is lower.
How do I find my air conditioner's wattage?
Look at the silver nameplate on the side of the unit or the EnergyGuide label. If only amps are listed, multiply amps by 115 volts to get approximate watts.
Is it cheaper to leave the AC on all day or turn it off?
Turning it off when nobody is in the room is cheaper. An air conditioner uses energy in proportion to how long it runs, and a room that warms up while you are out does not take more energy to cool back down than it would have taken to hold it cool all day.