How to estimate AC running cost
Size the load, then apply runtime and your tariff.
Enter the cooled area
Use the floor area served by the unit; add a little for open-plan or high-ceiling rooms.
Set realistic runtime
Use the hours per day the system actually runs during the hottest month.
Add the efficiency rating
SEER is on the unit label; a higher figure means less electricity for the same cooling.
What does this tool do?
An air conditioner running cost depends on how much heat it removes, how long it runs and how efficiently it does so. This calculator sizes a rough cooling load from floor area, converts it to electricity using the SEER rating and applies your tariff.
The Formula
Capacity (BTU/h) ≈ area × 25; kWh = capacity × hours × days ÷ SEER ÷ 1000; cost = kWh × rateFrequently Asked Questions
Why is my bill different from the estimate?
The calculation assumes full-load running. Mild weather lowers the cost while poor insulation, high ceilings, sunny windows and open doors raise it.
What SEER rating should I use?
Use the rating on the unit or its EnergyGuide label. Central systems commonly range from 14 to 20 SEER; higher ratings cost more upfront but use less electricity.