How many watts does a window AC use?
Updated
Running watts
1,200 W
Starting watts
3,600 W
Energy per day
9.6 kWh
A window AC typically draws about 1,200 watts while running and up to 3,600 watts for a second or two when the motor starts. At about 8 h of use a day, that is roughly 9.6 kWh per day. These are typical values from generator wattage charts: the label on your own appliance (or its EnergyGuide sticker) gives the exact figure.
What size generator do I need for a window AC?
Plan for at least 4,320 W: 3,600 W to get through the start-up surge, plus a 20% margin so the generator never runs flat out. Of the common sizes, a 5,000 W generator is the smallest that fits.
| Generator | Can it run a window AC? |
|---|---|
| 2,000 W | No |
| 3,500 W | No |
| 5,000 W | Yes |
| 7,500 W | Yes |
| 10,000 W | Yes |
| 15,000 W | Yes |
How long will a power station run a window AC?
Running continuously at 1,200 W, assuming 85% of the battery is usable. The station's AC output must also handle the 3,600 W start-up surge.
| Battery capacity | Runtime |
|---|---|
| 1,000 Wh | about 43 min |
| 2,000 Wh | about 1 h |
| 3,600 Wh | about 3 h |
Running more than one appliance?
Starting surges don't add up the way running watts do. Pick everything you want to power to get your real number.
Open the Generator Size Calculator for Your HomeFrequently asked questions
What size generator do I need to run a window AC?
At least 4,320 W: 3,600 W to cover the start-up surge, plus a 20% safety margin.
Can a 2,000 watt generator run a window AC?
No. It needs about 3,600 W for a second or two when it starts, more than 2,000 W.
Can a 3,500 watt generator run a window AC?
No. It needs about 3,600 W for a second or two when it starts, more than 3,500 W.
How long will a 1,000 Wh power station run a window AC?
About 43 min, assuming 85% usable capacity, as long as the station's AC output is rated for 3,600 W of surge.
Never run a generator indoors or in a garage: see the CPSC safety guide.