Air Conditioner Running Cost Calculator
Enter your air conditioner's BTU size, SEER efficiency rating, and usage hours to see exactly what it costs to cool your home — per hour, per day, per month, and per year.
Last verified: April 29, 2026
Per hour
$0.19
Per day
$1.55
Per month
$46
Per year
$186
- Power draw
- 1,125 W
- kWh per day
- 9.0 kWh
- kWh per season
- 1,080 kWh
- Cost per kWh
- $0.1745
Estimate only. Actual costs vary with temperature, thermostat setting, insulation, and humidity.
How this is calculated
The calculator converts BTU cooling capacity to watts using the SEER rating, then multiplies by usage hours to get energy consumed.
Power draw (watts) = BTU ÷ SEER
kWh per hour = Watts ÷ 1,000
kWh per day = kWh/hr × Hours/day
kWh per season = kWh/day × 30 × Months
Annual cost = kWh/season × Electricity rate
Example (18,000 BTU, SEER 16, 8 hrs/day, 4 months, $0.1745/kWh):
Watts = 18,000 ÷ 16 = 1,125 W
kWh/day = 1.125 × 8 = 9.0 kWh
kWh/season = 9.0 × 30 × 4 = 1,080 kWh
Annual cost = 1,080 × $0.1745 = $188Assumptions
- SEER rating is used as specified — actual efficiency varies with outdoor temperature and humidity
- Usage hours/day represent average runtime, not time thermostat is on
- "Cooling months" assumes 30 days per month for seasonal calculation
- Custom BTU field overrides the dropdown selection if filled in
- Does not include installation, maintenance, or refrigerant costs
Running cost by SEER rating (18,000 BTU, 8 hrs/day, 4 months)
| SEER Rating | Power (W) | kWh/season | Annual cost | vs SEER 13 |
|---|---|---|---|---|
| SEER 13 | 1,385 W | 1,329 kWh | $231.95/yr | — |
| SEER 15 ✓ ENERGY STAR | 1,200 W | 1,152 kWh | $201.02/yr | -$30.93 |
| SEER 16 ✓ ENERGY STAR | 1,125 W | 1,080 kWh | $188.46/yr | -$43.49 |
| SEER 18 ✓ ENERGY STAR | 1,000 W | 960 kWh | $167.52/yr | -$64.43 |
| SEER 20 ⭐ High efficiency | 900 W | 864 kWh | $150.77/yr | -$81.18 |
| SEER 25 ⭐ High efficiency | 720 W | 691 kWh | $120.61/yr | -$111.34 |
US average electricity rate $0.1745/kWh (EIA, 2026-04-27).
Frequently asked questions
What is a SEER rating? ▾
SEER (Seasonal Energy Efficiency Ratio) measures how efficiently an AC unit cools over an entire season. A SEER 16 unit produces 16 BTU of cooling per watt-hour of electricity. Higher SEER = less electricity used. The US minimum for new central AC units is SEER 14–15 depending on region. ENERGY STAR units are SEER 15+.
How do I find my AC's BTU rating? ▾
Check the nameplate label on the outdoor unit, the owner's manual, or the model number. Window units are typically 5,000–25,000 BTU. Central AC systems for homes are typically 18,000–60,000 BTU (1.5–5 tons). One ton of cooling = 12,000 BTU.
How many hours per day does a typical AC run? ▾
In hot summer months, a central AC typically runs 8–12 hours per day in warmer climates (Texas, Florida) and 4–8 hours in milder areas. Window units may run less. This calculator uses your estimated hours per day averaged across the cooling season.
Does running the AC at a lower temperature use more electricity? ▾
Yes. Every degree lower you set the thermostat increases energy use by roughly 3–5%. The DOE recommends 78°F (26°C) when home and higher when away. A smart thermostat can reduce AC costs by 10–15%.
What's the difference between EER and SEER? ▾
EER (Energy Efficiency Ratio) measures efficiency at a single peak condition (95°F outdoor, 80°F indoor). SEER measures efficiency across a whole season of varying conditions. SEER is a better predictor of your annual running cost. If you only have EER, multiply by approximately 1.1–1.2 to estimate SEER.
Sources
- U.S. EIA — Electric Power Monthly — US average residential electricity rate ($0.1745/kWh) (last checked 2026-04-29)
- U.S. Department of Energy — Air Conditioning — SEER definition, efficiency benchmarks and cooling tips (last checked 2026-04-29)
- ENERGY STAR — Most Efficient Central AC — ENERGY STAR SEER thresholds (last checked 2026-04-29)