Central AC vs Window Unit Cost Calculator
Cool one room or the whole house - priced side by side. Adjust the wattage, runtime and your own electricity rate below — every figure updates instantly in your browser, and nothing you type is sent anywhere.
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How this cost is calculated
The formula is kWh = watts ÷ 1000 × hours, then cost = kWh × your rate per kWh. Standing charges and tiered or time-of-use pricing are billed separately by your supplier, so treat these numbers as the marginal cost of running this appliance rather than a full bill.
For the full breakdown with regional price tables, read the detailed guide, or estimate your whole household on the home electricity bill calculator.
Frequently asked questions
Is central AC more expensive than window units?
Per room, yes: central AC costs roughly $150-$250 a month against $25-$60 for one window unit, but it becomes competitive once you are cooling four or more rooms.
How many kWh does central AC use per day?
A 3.5 kW system running 8 hours uses about 28 kWh a day, roughly $4.48 at $0.16/kWh.
Does a smart thermostat reduce central AC cost?
Typically 8-15%, mostly by avoiding cooling an empty house and by pre-cooling before peak time-of-use pricing.