A 3-ton central air conditioner in Oklahoma costs about $111.08 in July and $402 a year at 13.81¢/kWh; an 8,000 BTU window unit about $23.18 in July.
At 13.81¢/kWh — Oklahoma average, Jan–Aug 2026 (EIA). That is 24% below the U.S. average of 18.19¢.
| Efficiency | Per year | vs yours |
|---|---|---|
| SEER2 13.4 (min · North) | $429 | +$27.00 |
| SEER2 14.3 (min · South) | $402 | — |
| SEER2 15.2 (ENERGY STAR) | $378 | −$23.81 |
| SEER2 17 (ES average) | $338 | −$63.86 |
| Month | Full-load hours | 3-ton central | 8,000 BTU window |
|---|---|---|---|
| February | 2 | $0.64 | $0.13 |
| March | 9 | $3.00 | $0.63 |
| April | 22 | $7.51 | $1.57 |
| May | 91 | $31.74 | $6.62 |
| June | 216 | $75.27 | $15.70 |
| July | 319 | $111.08 | $23.18 |
| August | 300 | $104.43 | $21.79 |
| September | 158 | $54.89 | $11.45 |
| October | 37 | $12.87 | $2.68 |
| November | 2 | $0.64 | $0.13 |
DOE's room-AC test assumes 750 full-load hours a year for a typical U.S. home. We scale it by Oklahoma's population-weighted cooling degree days (1,875 ÷ 1,216) and spread it over the months the same way: 1,156 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. × 1,156 h = 2,911 kWh × 13.81¢ = $402.
The full method, material data and tips are on the main air conditioner cost calculator page.