How Much Does It Cost to Run a window AC?
A typical window AC uses about 900 watts, which costs about $0.16 per hour. Used 8 hours a day, that is $1.30 per day, $39 per month and about $473 per year at the US average of about 18 cents per kWh. Change the numbers below for your own model and rate.
Typical estimate: 8 hours of compressor running time a day in summer. These are typical estimates – check your own label or use a plug-in meter for exact figures.
Window AC running cost by electricity rate
Rates vary widely across the country. $0.12 is typical of low-cost areas, $0.18 is about the national average, and $0.25–$0.35 or more is common in high-cost areas such as parts of California, New England and Hawaii.
| Rate per kWh | Per hour | Per day | Per month | Per year |
|---|---|---|---|---|
| $0.12 | $0.108 | $0.86 | $26.28 | $315 |
| $0.18 | $0.162 | $1.30 | $39.42 | $473 |
| $0.25 | $0.225 | $1.80 | $54.76 | $657 |
| $0.35 | $0.315 | $2.52 | $76.66 | $920 |
Based on 900 W for 8 h/day; month = 30.42 days.
Cost by hours of use per day
| Hours per day | kWh per month | Per day | Per month | Per year |
|---|---|---|---|---|
| 4 h | 110 | $0.65 | $19.71 | $237 |
| 8 h | 219 | $1.30 | $39.42 | $473 |
| 12 h | 329 | $1.94 | $59.14 | $710 |
At 18 cents per kWh and 900 W.
Low, typical and high wattage
An 8,000–12,000 BTU window unit typically draws 700–1,100 W while the compressor runs; large 18,000+ BTU units can pull 1,400 W or more.
| Case | Watts | Per hour | Per month | Per year |
|---|---|---|---|---|
| Low | 500 | $0.090 | $21.90 | $263 |
| Typical | 900 | $0.162 | $39.42 | $473 |
| High | 1,440 | $0.259 | $63.08 | $757 |
At 8 h/day and 18 cents per kWh.
How it is calculated
900 W × 8 h ÷ 1,000 = 7.2 kWh per day
7.2 kWh × $0.18 = $1.30 per day
$1.30 × 30.42 days = $39.42 per month
How to cut the cost of running a window AC
- Check the EER or CEER on the label: a unit with a CEER of 12 uses about 17% less electricity than one rated 10 for the same cooling (CEER is BTU of cooling per watt-hour).
- Size it to the room. A unit that is too big cools quickly, cycles off before it removes humidity, and wastes starting surges.
- Seal gaps around the accordion side panels with foam strips – leaking air makes the compressor run longer.
- Clean the filter every couple of weeks and shade the outside of the unit from afternoon sun.
Frequently asked questions
How much does it cost to run a window AC per month?
At 18 cents per kWh, a typical 900 W window AC used 8 hours a day costs about $39.42 per month (219 kWh). That is about $473 a year.
How much does it cost to run a window AC per hour?
About $0.162 per hour at 18 cents per kWh, or $0.315 per hour if you pay 35 cents per kWh. Multiply by your hours of use to estimate any day.
Why does the cost of a window AC vary so much?
Wattage varies by model and setting – from 500 W to 1,440 W here. At the same 8 hours a day and 18 cents per kWh, that is $22 to $63 per month. Your electricity rate matters just as much: at 35 cents per kWh the typical unit costs $77 per month.