What does it cost to run an AC in Illinois?
At Illinois’s average electricity rate of 18.2¢/kWh, a typical 12,000 BTU air conditioner (EER 11, run 8 hours a day) costs about 19.9¢ an hour, $48 a month, or roughly $238 across a 5-month cooling season. Run your own numbers below.
Independent estimate for guidance only. Your real cost depends on the unit, thermostat setting, insulation and how hot it gets.
Why AC costs what it does in Illinois
Illinois homes pay about 18.2¢/kWh, which is 0.2¢ below the US average. Because the electricity rate is a straight multiplier on every kilowatt-hour your air conditioner uses, that puts Illinois around the middle for cooling costs. The biggest levers you control are the hours you run it and the unit’s efficiency.
Illinois electricity price trend
Average residential rate, monthly, May 2023 – Apr 2026. Up 15% over the period.
Source: U.S. Energy Information Administration (EIA), Electric Power Monthly · range 13.74–20.47¢/kWh
A worked example for Illinois
A 12,000 BTU unit at EER 11, run 8 hours a day:
Draws about 1091 watts. Change the size, efficiency and hours in the calculator above.
Offset it with solar
Cooling is one of the biggest summer power draws, so it’s exactly what rooftop solar is good at offsetting — the sun is strongest when your AC works hardest. See whether solar pays off in Illinois with our Illinois solar payback calculator, or check your EV charging cost too.