A 3-ton central air conditioner in Nebraska costs about $71.72 in July and $216 a year at 12.92¢/kWh; an 8,000 BTU window unit about $14.02 in July.
At 12.92¢/kWh — Nebraska average, Jan–Aug 2026 (EIA). That is 29% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $216 | — |
| SEER2 14.3 (min · South) | $202 | −$13.58 |
| SEER2 15.2 (ENERGY STAR) | $190 | −$25.56 |
| SEER2 17 (ES average) | $170 | −$45.70 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| March | 1 | $0.43 | $0.08 |
| April | 3 | $1.07 | $0.21 |
| May | 44 | $15.20 | $2.97 |
| June | 132 | $45.81 | $8.96 |
| July | 207 | $71.72 | $14.02 |
| August | 170 | $58.87 | $11.51 |
| September | 59 | $20.55 | $4.02 |
| October | 6 | $2.14 | $0.42 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Nebraska's population-weighted cooling degree days (1,008 ÷ 1,216) and spread it over the months the same way: 622 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. × 622 h = 1,670 kWh × 12.92¢ = $216.
The full method, material data and tips are on the main air conditioner cost calculator page.