How many watts does a window AC use?
Most window ACs use 450–1,500 watts while running (typically about 900 W) and 900–2,400 W for a few seconds when the motor or compressor starts. At the U.S. average rate of 18.16¢/kWh, a typical one costs about $10.30 a month ($124 a year, if used about 120 days a year).
Wattage depends mostly on size (BTU): see the ENERGY STAR table below for 5,000 to 18,000+ BTU units.
Cost to run a window AC: calculator
Real data from 597 ENERGY STAR models
Median measured on-mode power: 709 W (most models 500–1,200 W). Older or non-certified models usually use more. Costs assume 8 h/day, 120 days/yr.
| Median | Cost at 18.16¢ | |
|---|---|---|
| 5,000–6,000 BTU | 397 W | $69.21/yr |
| 8,000 BTU | 533 W | $92.92/yr |
| 10,000 BTU | 667 W | $116/yr |
| 12,000 BTU | 800 W | $139/yr |
| 14,000–15,000 BTU | 933 W | $163/yr |
| 18,000+ BTU | 1701 W | $297/yr |
Running vs starting watts
Running watts are what it draws while operating; they drive your electricity bill. Starting watts are a short surge when a motor or compressor kicks on; they matter for sizing a generator or power station.
| Source | Running | Starting |
|---|---|---|
| Champion Power Equipment generator wattage chart | 450–1,200 W | 900–2,400 W |
| Honda generator wattage chart (PDF) | 1,500 W | 2,200 W |
| EcoFlow appliance wattage chart | 800–1,500 W | 2,400–4,500 W |
| ENERGY STAR certified models (10th–90th percentile, 597 models) | 500–1200 W | — |
Will a power station run it?
A 1,000 Wh power station would run a typical window AC for about 0.9 hours (assuming 85% conversion efficiency). Look for at least 1,500 W continuous output and 3,900 W surge (peak). Check your power station or generator →
Cost by state
Based on the median ENERGY STAR model (709 W) for 8 hours a day, 120 days a year (681 kWh/yr).
Cost to run a window AC in every state
| State | Rate | Per month | Per year |
|---|---|---|---|
| Alabama | 16.33¢ | $9.26 | $111 |
| Alaska | 29.41¢ | $16.68 | $200 |
| Arizona | 15.05¢ | $8.54 | $102 |
| Arkansas | 14.37¢ | $8.15 | $97.81 |
| California | 29.75¢ | $16.87 | $202 |
| Colorado | 17.17¢ | $9.74 | $117 |
| Connecticut | 24.51¢ | $13.90 | $167 |
| Delaware | 18.70¢ | $10.61 | $127 |
| District of Columbia | 25.98¢ | $14.74 | $177 |
| Florida | 14.99¢ | $8.50 | $102 |
| Georgia | 15.90¢ | $9.02 | $108 |
| Hawaii | 47.18¢ | $26.76 | $321 |
| Idaho | 13.37¢ | $7.58 | $91.00 |
| Illinois | 19.32¢ | $10.96 | $131 |
| Indiana | 17.02¢ | $9.65 | $116 |
| Iowa | 17.06¢ | $9.68 | $116 |
| Kansas | 15.47¢ | $8.77 | $105 |
| Kentucky | 13.80¢ | $7.83 | $93.93 |
| Louisiana | 12.87¢ | $7.30 | $87.60 |
| Maine | 32.11¢ | $18.21 | $219 |
| Maryland | 21.40¢ | $12.14 | $146 |
| Massachusetts | 30.48¢ | $17.29 | $207 |
| Michigan | 22.99¢ | $13.04 | $156 |
| Minnesota | 17.20¢ | $9.76 | $117 |
| Mississippi | 14.43¢ | $8.18 | $98.22 |
| Missouri | 16.02¢ | $9.09 | $109 |
| Montana | 15.57¢ | $8.83 | $106 |
| Nebraska | 13.54¢ | $7.68 | $92.16 |
| Nevada | 12.72¢ | $7.21 | $86.58 |
| New Hampshire | 27.64¢ | $15.68 | $188 |
| New Jersey | 24.61¢ | $13.96 | $168 |
| New Mexico | 16.51¢ | $9.36 | $112 |
| New York | 28.65¢ | $16.25 | $195 |
| North Carolina | 14.95¢ | $8.48 | $102 |
| North Dakota | 13.31¢ | $7.55 | $90.59 |
| Ohio | 19.38¢ | $10.99 | $132 |
| Oklahoma | 14.82¢ | $8.41 | $101 |
| Oregon | 15.92¢ | $9.03 | $108 |
| Pennsylvania | 21.77¢ | $12.35 | $148 |
| Rhode Island | 28.18¢ | $15.98 | $192 |
| South Carolina | 15.76¢ | $8.94 | $107 |
| South Dakota | 15.15¢ | $8.59 | $103 |
| Tennessee | 13.42¢ | $7.61 | $91.34 |
| Texas | 15.91¢ | $9.02 | $108 |
| Utah | 13.31¢ | $7.55 | $90.59 |
| Vermont | 23.84¢ | $13.52 | $162 |
| Virginia | 17.64¢ | $10.01 | $120 |
| Washington | 14.63¢ | $8.30 | $99.58 |
| West Virginia | 16.31¢ | $9.25 | $111 |
| Wisconsin | 19.41¢ | $11.01 | $132 |
| Wyoming | 14.43¢ | $8.18 | $98.22 |
FAQ
How many watts does a window AC use?
Most window ACs use 450–1,500 watts while running (typically about 900 W) and 900–2,400 W for a few seconds when the motor or compressor starts. At the U.S. average rate of 18.16¢/kWh, a typical one costs about $10.30 a month ($124 a year, if used about 120 days a year).
What are the starting watts of a window AC?
About 900–2,400 W for a second or two at start-up. This matters when sizing a generator or power station, not for your electricity bill.
How much does it cost to run a window AC?
About $10.30 a month at the U.S. average rate (18.16¢/kWh, August 2026), based on the median ENERGY STAR model (709 W) for 8 hours a day, 120 days a year (681 kWh/yr). In the cheapest state it's about $7.21 a month; in the most expensive, $26.76.
How many kWh does a window AC use?
About 681 kWh a year (57 kWh a month), based on the median ENERGY STAR model (709 W) for 8 hours a day, 120 days a year (681 kWh/yr).
Can a power station or generator run a window AC?
A 1,000 Wh power station would run a typical window AC for about 0.9 hours. Look for at least 1,500 W continuous output and 3,900 W surge (peak).