Is a window unit cheaper than central air conditioning?

For one room, yes, easily. For a whole house, central air is usually cheaper than running a window unit in every room.

At the default usage on each page, central air conditioner costs about 3.3× as much to run as window air conditioner — $1,125 against $337 a year.

Why window air conditioner wins, and when it does not

• Central air cools the entire house whether you are in it or not, which is waste if you occupy one room.
• Ducted systems also lose 20–30% of their cooling into unconditioned attics and crawlspaces before it reaches a room.
• The crossover is roughly three rooms. Beyond that, central air's efficiency of scale wins.

What the difference is worth where you live

The 3.3× above holds at any price: both a window air conditioner and a central air conditioner scale with whatever you pay per kilowatt-hour. The money does not. Choosing window air conditioner over central air conditioner saves about $787 a year at the U.S. average, and $2,263 a year in Hawaii at 52.72¢ — against $563 in Nevada, the cheapest jurisdiction in the country. Swapping central air conditioner for window air conditioner is worth 4.0× as much in Hawaii as in Nevada, so what you pay per kilowatt-hour decides this more than the wattage on either label.

Both figures use each appliance’s typical wattage and default usage at the U.S. average of 18.34¢ per kilowatt-hour, and exclude fixed charges, taxes and time-of-use rates. Change the wattage, usage or state on either appliance’s own page to compare them on your terms, or read how to check a running-cost figure before trusting any of them.