A 3-ton central air conditioner in Minnesota costs about $49.58 in July and $132 a year at 16.44¢/kWh; an 8,000 BTU window unit about $9.69 in July.
At 16.44¢/kWh — Minnesota average, Jan–Aug 2026 (EIA). That is 10% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $132 | — |
| SEER2 14.3 (min · South) | $123 | −$8.28 |
| SEER2 15.2 (ENERGY STAR) | $116 | −$15.58 |
| SEER2 17 (ES average) | $104 | −$27.86 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| April | 1 | $0.54 | $0.11 |
| May | 23 | $10.35 | $2.02 |
| June | 64 | $28.06 | $5.49 |
| July | 112 | $49.58 | $9.69 |
| August | 81 | $35.96 | $7.03 |
| September | 15 | $6.54 | $1.28 |
| October | 1 | $0.54 | $0.11 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Minnesota's population-weighted cooling degree days (483 ÷ 1,216) and spread it over the months the same way: 298 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. × 298 h = 800 kWh × 16.44¢ = $132.
The full method, material data and tips are on the main air conditioner cost calculator page.