Air Conditioner Efficiency Savings Calculator
Try an example
1 ton = 12,000 Btu/h; model numbers often show it as 24, 36, 48 (thousand Btu)
U.S. residential average is about $0.17; check your bill
Central air conditioners typically last 12–17 years
The hours the unit would need at full output to deliver a season's cooling. It actually runs longer, cycling at part load.
Typical by climate
Unit B saves
$238 a year
It uses 37% less electricity for the same cooling, 1,401 kWh a year, with most of the saving on summer bills.
The extra $8,000 would take 34 years to recover, longer than the 15 years you expect to keep it: you end $4,427 behind.
Running cost
| Unit | SEER2 | kWh a year | Cost a year |
|---|---|---|---|
| A | 9.5 | 3,770 | $641 |
| B | 15.2 | 2,368 | $403 |
kWh = tons × 12,000 Btu/h × hours ÷ (SEER2 × 1,000). SEER ratings are converted with SEER2 ≈ 0.955 × SEER, the ratio between the old and new federal minimums. The current minimum for new central air conditioners is 13.4 SEER2 in northern states and 14.3 SEER2 in the South and Southwest.
Ratings assume correct sizing, refrigerant charge and airflow. Leaky ducts, a dirty coil or an oversized unit can erase the difference between two ratings, so get a Manual J load calculation with any quote. Variable-speed units also dehumidify better, which the rating does not capture. If the old unit needs replacing anyway, compare the basic and efficient options instead of the old unit: only the price difference has to pay itself back.
Compare the running cost of two air conditioners by their efficiency ratings, in SEER2 for units made since 2023 or SEER for older ones, and see the yearly saving, the share of electricity saved and how long the price difference takes to pay back.
Formula
Worked Example
The old 10 SEER unit rates about 9.55 SEER2 and uses 3,770 kWh a year against 2,368 kWh for the new one. Saving 1,401 kWh at $0.17 is $238 a year, far too little to justify replacing a working unit; in a hot climate with 3,000 hours the same comparison pays back three times faster.
Frequently Asked Questions
What is the difference between SEER and SEER2?
SEER2 is the rating used since January 2023, measured with higher duct static pressure that is closer to real installations, so it reads about 4.5% lower than SEER for the same unit. The old 14 and 15 SEER minimums became 13.4 and 14.3 SEER2.
What is the minimum SEER2 rating in 2026?
For new central air conditioners, 13.4 SEER2 in northern states and 14.3 SEER2 in the Southeast and Southwest (for split systems under 45,000 BTU/h). Heat pumps must reach 14.3 SEER2 everywhere.
Is a higher SEER2 unit worth the extra cost?
Compare the price difference over the basic unit with the yearly saving. It pays most in hot climates with long cooling seasons and high electricity prices. In a mild climate the premium for a top-rated unit can take longer to recover than the unit lasts.
Common Mistakes
- !Comparing an old unit's SEER directly with a new unit's SEER2, which understates the improvement.
- !Expecting the rating's savings from an oversized unit or leaky ducts, which can erase the difference.