A 3-ton central air conditioner in Arizona costs about $157.41 in July and $682 a year at 15.36¢/kWh; an 8,000 BTU window unit about $32.84 in July.
At 15.36¢/kWh — Arizona average, Jan–Aug 2026 (EIA). That is 16% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $728 | +$45.83 |
| SEER2 14.3 (min · South) | $682 | — |
| SEER2 15.2 (ENERGY STAR) | $642 | −$40.40 |
| SEER2 17 (ES average) | $574 | −$108 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| January | 2 | $0.72 | $0.15 |
| February | 7 | $2.86 | $0.60 |
| March | 23 | $8.82 | $1.84 |
| April | 68 | $26.23 | $5.47 |
| May | 169 | $65.35 | $13.64 |
| June | 316 | $122.35 | $25.53 |
| July | 407 | $157.41 | $32.84 |
| August | 378 | $146.20 | $30.50 |
| September | 268 | $103.75 | $21.65 |
| October | 110 | $42.69 | $8.91 |
| November | 15 | $5.72 | $1.19 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Arizona's population-weighted cooling degree days (2,861 ÷ 1,216) and spread it over the months the same way: 1,765 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. × 1,765 h = 4,442 kWh × 15.36¢ = $682.
The full method, material data and tips are on the main air conditioner cost calculator page.