SEER2 Savings Calculator
Compare the yearly electricity use and cost of two air conditioners or heat pumps by SEER2 rating, with a simple payback.
What SEER2 measures
SEER2, the seasonal energy efficiency ratio, is the cooling delivered over a typical season in BTU divided by the electricity used in watt-hours. A higher number means less electricity for the same cooling. Since January 2023, US ratings use the SEER2 test procedure, which assumes higher external static pressure, closer to real duct systems, so SEER2 numbers are about 4 to 5% lower than old SEER numbers for the same equipment. The current federal minimum for new split air conditioners under 45,000 BTU/h is 13.4 SEER2 in the northern region and 14.3 SEER2 in the southeast and southwest.
The calculation
Annual electricity use is capacity × full-load cooling hours ÷ (SEER2 × 1,000). A 3-ton, 36,000 BTU/h system running the equivalent of 1,200 full-load hours a year at SEER2 10 uses 36,000 × 1,200 ÷ 10,000 = 4,320 kWh. At SEER2 16, it uses 2,700 kWh. At 17 cents per kWh, the saving is 1,620 kWh, or $275.40 a year. If the more efficient unit costs $1,500 more, the simple payback is 5.4 years, before rebates or tax credits that can shorten it considerably.
Diminishing returns
Each additional point of SEER2 saves less than the one before, because electricity use is proportional to 1 ÷ SEER2. Going from 10 to 16 saves 1,620 kWh a year in the example; going from 16 to 20 saves only 540 kWh, $91.80. A common misconception is that the highest rating is always the best investment. In a mild climate with few cooling hours, a mid-range unit often pays back faster; in a hot climate with 2,000 or more hours, high-efficiency variable-speed equipment can justify its price.
Cooling hours and real results
The biggest uncertainty is the number of full-load cooling hours, not the rating. It varies from a few hundred a year in cool northern climates to over 2,000 in the hottest parts of the southern US. Your utility bills give the best estimate: compare summer and spring electricity use. Real savings also depend on installation. A high-SEER2 unit on leaky, undersized ducts or with the wrong refrigerant charge can perform worse than its rating, so commissioning matters as much as the label.
How to use it
- Enter the cooling capacity in BTU/h, 12,000 per ton.
- Enter your estimated full-load cooling hours per year and your electricity price.
- Enter the SEER2 rating of the current system and of the one you are considering.
- Optionally enter the extra cost of the more efficient unit to see the simple payback.
Questions from the job site
How much money does a higher SEER2 save?
It depends on capacity, cooling hours and electricity price. A 3-ton system running 1,200 full-load hours at 17 cents per kWh saves about $275 a year going from SEER2 10 to 16, but only about $92 more going from 16 to 20, because savings shrink as the rating rises.
What is the difference between SEER and SEER2?
SEER2 uses a test procedure introduced in the US in 2023 with higher external static pressure, closer to real duct systems. The same equipment rates about 4 to 5% lower in SEER2 than in the old SEER, so a 14 SEER unit is roughly 13.4 SEER2.
How many cooling hours does an air conditioner run per year?
From a few hundred full-load hours in cool climates to over 2,000 in hot, humid ones. Full-load hours are the equivalent number of hours at full capacity; a system that runs at half capacity for 10 hours counts as 5 full-load hours.
Is it worth buying the highest SEER2 unit?
Only if you have many cooling hours, high electricity prices or generous rebates. In mild climates the extra cost of the top-rated units may take longer to recover than the equipment lasts. Proper sizing and duct sealing often save more than a few extra SEER2 points.
Disclaimer: HVAC results are estimates from simplified methods and the values you enter. They are not a Manual J, S or D design and must not replace one for equipment selection or permits. Gas, electrical and refrigerant work must be carried out by licensed technicians to local codes, and combustion appliances need working carbon monoxide alarms.