A 3-ton central air conditioner in Indiana costs about $80.47 in July and $252 a year at 17.04¢/kWh; an 8,000 BTU window unit about $15.73 in July.
At 17.04¢/kWh — Indiana average, Jan–Aug 2026 (EIA). That is 6% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $252 | — |
| SEER2 14.3 (min · South) | $237 | −$15.89 |
| SEER2 15.2 (ENERGY STAR) | $223 | −$29.89 |
| SEER2 17 (ES average) | $199 | −$53.45 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| March | 1 | $0.56 | $0.11 |
| April | 2 | $1.13 | $0.22 |
| May | 46 | $21.18 | $4.14 |
| June | 117 | $53.37 | $10.43 |
| July | 176 | $80.47 | $15.73 |
| August | 144 | $65.79 | $12.86 |
| September | 57 | $25.98 | $5.08 |
| October | 9 | $3.95 | $0.77 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Indiana's population-weighted cooling degree days (894 ÷ 1,216) and spread it over the months the same way: 551 hours a year. Your thermostat setting and insulation move this a lot — switch the calculator to your own hours if you know them.
3 tons = 36,000 BTU/h ÷ SEER2 13.4 = 2,687 W. × 551 h = 1,481 kWh × 17.04¢ = $252.
The full method, material data and tips are on the main air conditioner cost calculator page.