A 3-ton central air conditioner in Alabama costs about $116.64 in July and $478 a year at 16.51¢/kWh; an 8,000 BTU window unit about $24.34 in July.
At 16.51¢/kWh — Alabama average, Jan–Aug 2026 (EIA). That is 9% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $510 | +$32.11 |
| SEER2 14.3 (min · South) | $478 | — |
| SEER2 15.2 (ENERGY STAR) | $450 | −$28.31 |
| SEER2 17 (ES average) | $402 | −$75.93 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| January | 7 | $3.08 | $0.64 |
| February | 4 | $1.54 | $0.32 |
| March | 17 | $6.92 | $1.44 |
| April | 28 | $11.79 | $2.46 |
| May | 110 | $45.63 | $9.52 |
| June | 212 | $88.19 | $18.40 |
| July | 281 | $116.64 | $24.34 |
| August | 265 | $109.98 | $22.95 |
| September | 165 | $68.70 | $14.34 |
| October | 49 | $20.51 | $4.28 |
| November | 9 | $3.59 | $0.75 |
| December | 4 | $1.54 | $0.32 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Alabama's population-weighted cooling degree days (1,865 ÷ 1,216) and spread it over the months the same way: 1,150 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 14.3 = 2,517 W. × 1,150 h = 2,896 kWh × 16.51¢ = $478.
The full method, material data and tips are on the main air conditioner cost calculator page.