A 3-ton central air conditioner in New Jersey costs about $112.57 in July and $306 a year at 24.09¢/kWh; an 8,000 BTU window unit about $22.01 in July.
At 24.09¢/kWh — New Jersey average, Jan–Aug 2026 (EIA). That is 32% above the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $306 | — |
| SEER2 14.3 (min · South) | $287 | −$19.24 |
| SEER2 15.2 (ENERGY STAR) | $270 | −$36.21 |
| SEER2 17 (ES average) | $241 | −$64.75 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| May | 20 | $13.17 | $2.58 |
| June | 87 | $56.28 | $11.00 |
| July | 174 | $112.57 | $22.01 |
| August | 141 | $91.41 | $17.87 |
| September | 45 | $29.14 | $5.70 |
| October | 5 | $3.19 | $0.62 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by New Jersey's population-weighted cooling degree days (766 ÷ 1,216) and spread it over the months the same way: 472 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. × 472 h = 1,269 kWh × 24.09¢ = $306.
The full method, material data and tips are on the main air conditioner cost calculator page.