Cost to run a window air conditioner per hour and month
What a window air conditioner costs
At 17 cents a kilowatt hour, a window air conditioner costs 15.3 cents an hour while it is drawing power. 6 hours a day with 60 percent average draw is 3.24 kWh a day, $16.52 a month and $201.04 a year. Change any of those three numbers in the calculator and the answer moves with them, because there is nothing else in the sum.
The label figure is 900 watts. That is what the device draws while it is working, not what it draws around the clock.
| Hours of use a day | Energy a day | Cost a month | Cost a year |
|---|---|---|---|
| 1 h | 0.54 kWh | $2.75 | $33.51 |
| 2 h | 1.08 kWh | $5.51 | $67.01 |
| 4 h | 2.16 kWh | $11.02 | $134.03 |
| 6 h | 3.24 kWh | $16.52 | $201.04 |
| 8 h | 4.32 kWh | $22.03 | $268.06 |
What changes the number
- The 900 W is compressor plus fan while cooling. Once the room reaches the set temperature the compressor cycles off, which is why the duty cycle matters more than the hours.
- A unit that is too small for the room never reaches the set point, never cycles, and runs at full draw the whole time. That costs more than the bigger unit it replaced.
- Sealing the gap around the unit matters more than the star rating. A loose window kit lets hot air back in and the compressor never stops.
Find your own wattage
On the rating plate behind the front grille or on the side of the casing. The cooling capacity in BTU is a different number and does not tell you the running cost.
What this does not include
It does not include a second unit in another room, and it assumes the thermostat setting is reachable by the unit.
Check it against your own numbers
The [running cost calculator](../index.html?device=window-ac) opens with this device already selected and its wattage filled in. Replace the wattage with your own reading, set the hours you actually use, and the monthly and yearly figures update in place.
Related: [A 1,500 W space heater](../space-heater/index.html), [An electric blanket](../electric-blanket/index.html), [A dehumidifier](../dehumidifier/index.html).