Is a window air conditioner cheaper to run than a portable?

Yes, and by more than the wattage suggests, because a single-hose portable fights its own exhaust.

At the default usage on each page, portable air conditioner costs about 1.2× as much to run as window air conditioner — $412 against $337 a year.

Why window air conditioner wins, and when it does not

• A single-hose portable blows conditioned indoor air out of the window. That air is replaced by unconditioned air pulled in through every gap in the building.
• The unit is then cooling air it just helped bring in, so real-world performance falls well below the rated figure.
• A dual-hose portable avoids this and closes most of the gap, but a window unit still normally wins.

What the difference is worth where you live

The 1.2× above holds at any price: both a window air conditioner and a portable air conditioner scale with whatever you pay per kilowatt-hour. The money does not. Choosing window air conditioner over portable air conditioner saves about $74.97 a year at the U.S. average, and $216 a year in Hawaii at 52.72¢ — against $53.59 in Nevada, the cheapest jurisdiction in the country. Swapping portable 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.