Air Conditioner Running Cost Calculator
Estimate what a air conditioner really costs to run, using wattage ranges and usage patterns specific to this appliance — not a one-size-fits-all average.
Air conditioning is usually the single largest line item on a summer electricity bill, and unlike a fridge that draws a steady load year-round, an AC unit’s cost swings wildly with the weather, the type of unit, and how many hours a day you run it. A window unit cooling one bedroom and a central system cooling a whole house can differ by a factor of three or more in wattage, so a single "air conditioner = 1500W" figure is almost useless for estimating your real bill.
The other thing that makes AC cost hard to pin down is the efficiency rating. Two units with the same cooling output can pull very different amounts of power depending on their EER or SEER rating, and an older, poorly maintained unit can quietly cost 30-40% more to run than its nameplate suggests. That is why the calculator below lets you set the exact wattage and runtime for your situation rather than guessing from an average.
Air Conditioner
Climate
Tip: Raising the thermostat by 1°C can cut cooling costs by up to 10%.
$62.10
365.3 kWh per month
Per day
$2.04
12 kWh
Per year
$744.6
4,380 kWh
Central and window AC units are among the largest home energy users, especially in summer.
Estimate based on typical usage.
Air Conditioner power by type
Wattage isn't a single number. It ranges from about 900W to 3,500W depending on the type, so match the row closest to yours.
Window unit (small room)
Cools ~150-250 sq ft, common in bedrooms and studios.
Window unit (large room)
Higher BTU units for open-plan or larger rooms.
Portable AC
Less efficient than window units for the same cooling.
Ductless mini-split
Efficient inverter-driven, cools one to two zones.
Central AC
Whole-home cooling; the compressor dominates the load.
What actually drives your AC cost
Runtime hours matter more than almost anything else. An AC that runs 4 hours in the evening costs half of one that runs 8 hours, and one left on 24/7 during a heatwave can dominate the entire bill. Set the daily hours slider to match how you really use it, not the best case.
EER and SEER ratings measure how much cooling you get per watt. A unit rated SEER 20 uses roughly half the power of a SEER 10 unit for the same cooling, so if your bill feels high, the age and rating of the unit is the first thing to check. Thermostat setpoint also compounds: every degree cooler you ask for makes the compressor run longer.
How to cut your air conditioner running cost
Raise the setpoint a few degrees
Each degree warmer on the thermostat cuts runtime meaningfully. A ceiling fan lets you sit comfortably a couple of degrees warmer, so the AC cycles less.
Cool zones, not the whole house
A mini-split or window unit cooling only the rooms you use can beat running central AC for an empty house. Close vents and doors to unused rooms.
Service the unit and clean filters
A clogged filter or dirty coil forces the compressor to work longer for the same cooling. Cleaning them is the cheapest efficiency upgrade there is.
Consider an inverter unit for heavy use
If you cool for many hours a day, an inverter-driven mini-split with a high SEER can pay back its cost through lower runtime power draw.
Frequently asked questions
Running a 1,500W unit for 8 overnight hours at $0.19/kWh costs about $2.28 a night, or roughly $68 a month if used every night. A small 900W window unit would be closer to $1.37 a night. Use the calculator to plug in your own wattage and rate.
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