How Much Electricity Does a Window Air Conditioner Use?
So how much electricity does a window air conditioner use? A window air conditioner typically draws 500 to 1,500 watts depending on its cooling capacity (BTU rating), with larger units built for bigger rooms drawing more. Because it's a compressor-based appliance that can run for hours at a stretch on a hot day, it's one of the bigger seasonal costs in the house — use the calculator below with your own unit's wattage and rate for a real number.
Calculate your cost to run a window air conditioner
Enter your rate to see your estimate.
What affects how much electricity a window air conditioner uses
BTU rating (cooling capacity) is the main driver: a small 6,000 BTU unit sized for one bedroom draws far less than a 12,000 BTU unit sized for a larger space. Energy efficiency ratio (EER) matters too, since a more efficient unit uses less electricity to deliver the same cooling. Like other compressor-based appliances, a window AC cycles on and off once it reaches the thermostat's target temperature, so its real average draw over a full day is somewhat below its running wattage.
How to reduce your window AC's electricity use
- Set the thermostat a few degrees higher than you would with central air; every degree closer to outdoor temperature reduces runtime
- Use a programmable or smart timer so it isn't cooling an empty room
- Keep the filter clean, since a clogged filter makes the compressor work harder
- Seal gaps around the unit and close blinds during peak sun to reduce the cooling load
Typical wattage figure: roughly 500-1,500 W depending on BTU rating (5,000-12,000 BTU). Source: Commonly cited estimate; ENERGY STAR publishes BTU sizing guidance but not a running-wattage table. (This is a commonly cited estimate, not a government-published figure.) This wattage range is a typical estimate, not a government-published figure. We review this figure periodically and update it if the source changes; last checked September 2026.
Frequently asked questions
How many watts does a window air conditioner use?
Typical window units draw roughly 500 to 1,500 watts depending on BTU rating, with common sizes running from about 720 watts (6,000 BTU) up to around 1,500 watts (10,000-12,000 BTU), based on commonly cited wattage references. This is a commonly cited estimate rather than a government-published figure; check your own unit's nameplate for its exact rating.
How much does it cost to run a window AC?
A 900-watt unit run 6 hours a day at the U.S. average rate of about 16.5 cents/kWh costs roughly $0.89 a day, or about $27 a month during cooling season. Use the calculator above with your own unit's wattage and rate for an exact figure.
Is a bigger window AC always better?
No — an oversized unit for the room cools too quickly without running long enough to properly remove humidity, which can leave a room feeling clammy even at a cool temperature. Matching BTU rating to room size, rather than just buying the biggest unit available, generally gives better comfort and lower cost.
How can I reduce how much electricity my window AC uses?
Set the thermostat as high as still feels comfortable, since every degree closer to the outdoor temperature meaningfully cuts runtime. Keeping the filter clean, sealing air leaks around the unit, and closing blinds during the hottest part of the day all reduce how hard the compressor has to work.
This page provides estimates based on commonly cited wattage figures and the numbers you enter, not a government-published table. Actual electricity cost depends on your specific unit's BTU rating, efficiency, and settings.