A 3-ton central air conditioner in Virginia costs about $87.90 in July and $276 a year at 16.95¢/kWh; an 8,000 BTU window unit about $18.34 in July.
At 16.95¢/kWh — Virginia average, Jan–Aug 2026 (EIA). That is 7% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $295 | +$18.54 |
| SEER2 14.3 (min · South) | $276 | — |
| SEER2 15.2 (ENERGY STAR) | $260 | −$16.35 |
| SEER2 17 (ES average) | $232 | −$43.85 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| March | 1 | $0.53 | $0.11 |
| April | 4 | $1.58 | $0.33 |
| May | 41 | $17.63 | $3.68 |
| June | 126 | $53.95 | $11.26 |
| July | 206 | $87.90 | $18.34 |
| August | 175 | $74.75 | $15.60 |
| September | 80 | $33.95 | $7.08 |
| October | 13 | $5.53 | $1.15 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Virginia's population-weighted cooling degree days (1,049 ÷ 1,216) and spread it over the months the same way: 647 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. × 647 h = 1,629 kWh × 16.95¢ = $276.
The full method, material data and tips are on the main air conditioner cost calculator page.