What SEER and SEER2 mean
SEER (Seasonal Energy Efficiency Ratio) is the cooling output of an air conditioner or heat pump over a typical cooling season divided by the electricity it uses. Higher numbers mean lower bills. Since January 2023, US ratings use SEER2, measured with higher external static pressure that better reflects real ductwork; a unit's SEER2 value is about 5 % lower than its old SEER value.
Yearly kWh = capacity (BTU/h) × full-load cooling hours ÷ SEER ÷ 1000
Minimum efficiency today
New central air conditioners sold in the northern US must reach at least SEER2 13.4; in the southeast and southwest the minimum is SEER2 14.3 (larger units 13.8). Units installed before 2006 were often SEER 10 or lower, so replacing them typically cuts cooling electricity by 30 – 45 %.
Example savings (3-ton system, $0.17/kWh)
| Climate | SEER 10 cost | SEER2 16 cost | Yearly savings |
|---|
| Mild (1,000 h) | $612 | $363 | ≈ $250 |
| Warm (1,400 h) | $857 | $509 | ≈ $350 |
| Hot (2,000 h) | $1,224 | $727 | ≈ $500 |
Is a higher SEER worth it?
The jump from an old SEER 10 unit to any new system is large. Going from a minimum-efficiency new unit to a premium variable-speed model saves less per year, so the payback depends on your climate and electricity price. In hot regions with long cooling seasons, SEER2 17 – 20 often pays back within the system's 15-year life; in cool climates the extra cost may not. Variable-speed systems also run longer at low speed, which improves humidity control and comfort.
Other factors that affect your bill
- Correct sizing: an oversized unit short-cycles, removes less humidity and wastes energy.
- Ductwork: leaky ducts in attics can lose 20 – 30 % of cooling – sealing them can save as much as a SEER upgrade.
- Installation quality: refrigerant charge and airflow set to specification.
- Thermostat settings: each degree warmer saves a few percent of cooling energy.
- Maintenance: clean filters and coils keep efficiency close to the rating.
Getting quotes
Ask for at least three quotes that include a load calculation, the matched AHRI certificate number for the outdoor and indoor units, warranty terms and any local utility rebates. Compare the total installed price and expected yearly operating cost, not just the efficiency number.
Frequently asked questions
How much can I save with a new SEER2 16 air conditioner?
Replacing an old SEER 10 unit typically saves 35 – 40 % of cooling electricity – about $250 – $500 a year for a 3-ton system, depending on climate and electricity price.
What is the difference between SEER and SEER2?
SEER2 uses a test with higher duct resistance, so ratings are about 5 % lower than SEER for the same equipment.
Is a SEER2 20 air conditioner worth it?
In hot climates with long cooling seasons and high electricity prices, often yes. In mild climates the extra cost may not pay back on energy alone.
What SEER is my old air conditioner?
Units installed before 2006 were usually SEER 10 or lower; 2006 – 2014 units typically SEER 13; 2015 – 2022 units SEER 14 in the South.
How long does a central air conditioner last?
Typically 12 – 17 years with regular maintenance.
About SEERsense
SEERsense is an independent, free calculator for comparing the operating cost of air conditioners and heat pumps by SEER and SEER2 efficiency ratings. Results are estimates using typical cooling hours; your usage, ductwork and installation quality affect real savings. We are not an HVAC contractor or manufacturer.
Every formula on this page runs entirely in your web browser. The numbers you type are never uploaded, stored or shared. Our goal is simple: give you an honest starting point so you can compare product specifications with confidence and avoid paying for capacity you do not need – or buying something too small to do the job.
The methodology combines widely published engineering rules of thumb, manufacturer data sheets and the electrical code practices that installers use every day. We review the assumptions regularly and update the calculator when typical product specifications change.
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Last updated: October 28, 2026
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The calculator and articles on this website are provided free of charge for general information and educational purposes only. Results are estimates based on typical values and simplifying assumptions; real-world performance depends on the specific product, installation, climate, wiring and how you use your equipment.
Nothing on this site is professional engineering, electrical or financial advice. Always follow the manufacturer's instructions and local electrical codes, and have permanent installations, transfer switches and grid-connected systems designed and installed by a licensed electrician or qualified installer. Never operate fuel-burning generators indoors or in enclosed spaces – carbon monoxide can kill within minutes.
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