How much does a window a/c cost to run?

Window units are smaller than central systems but still pull substantial power when running, typically 3,000–6,000 watts depending on size. Efficiency drops if the unit is undersized for the room or if air leaks around the edges.

Typical running cost (18.83¢/kWh, U.S. average, 2026-04)

BasisCost
Per hour (while running, 900 W typical)$0.17
Per day (8 h/day, 7/7 days)$1.36
Per month$41.27
Per year$495.19
Hourly range (small 500 W – large 1400 W)$0.094 – $0.26
Save: Seal gaps around the unit frame and close curtains during peak heat hours to reduce the cooling load.

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