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Quick answer: SEER2 measures how efficiently an air conditioner or heat pump cools over a whole season; higher is better. New split-system central ACs must meet at least 13.4 SEER2 in the North and 14.3 SEER2 in the Southeast and Southwest (for units under 45,000 BTU/h). Split-system heat pumps need at least 14.3 SEER2 and 7.5 HSPF2 nationwide. Paying for a higher rating makes the most sense where you run the AC a lot.
Every AC and heat pump quote is full of acronyms: SEER2, EER2, HSPF2. They’re the numbers that decide how much you’ll pay to run the system for the next 15 years, so it’s worth knowing what they mean. This guide explains each rating, the current federal minimums, and a simple way to estimate whether a higher-efficiency model is worth the extra money for you.
What SEER2 means
SEER stands for Seasonal Energy Efficiency Ratio: the cooling a system delivers over a typical season, divided by the electricity it uses. A higher SEER2 means more cooling per kilowatt-hour, so lower bills for the same comfort.
The “2” marks the newer test procedure that took effect on January 1, 2023 (AHRI). The SEER2 test better reflects real-world conditions, such as the resistance of typical ductwork, so the numbers are lower than the old SEER numbers for the same unit. That’s why you’ll see equivalents like “13.4 SEER2 (equivalent to 14 SEER)”. When comparing quotes, make sure every number is SEER2, not a mix of old and new ratings.
The other ratings on the label
| Rating | What it measures | Applies to |
|---|---|---|
| SEER2 | Seasonal cooling efficiency | Central ACs and heat pumps |
| EER2 | Cooling efficiency at a single hot condition (a peak-heat snapshot) | Central ACs and heat pumps; required minimums in the Southwest |
| HSPF2 | Seasonal heating efficiency | Heat pumps only |
| AFUE | Share of fuel turned into heat | Furnaces and boilers |
In very hot, dry climates, EER2 matters because it describes how the system performs on the hottest afternoons, when it works hardest. In cold climates, HSPF2 and the heating capacity at low temperatures matter more than SEER2. See our cold-weather heat pump guide for those specs.
Federal minimums in 2026
Minimum efficiency for new central air conditioners depends on where you live. Here are the current split-system standards as summarized by AHRI:
| Equipment and region | Under 45,000 BTU/h | 45,000 BTU/h and up |
|---|---|---|
| Split-system AC, North | 13.4 SEER2 | 13.4 SEER2 |
| Split-system AC, Southeast | 14.3 SEER2 | 13.8 SEER2 |
| Split-system AC, Southwest | 14.3 SEER2 + 11.7/9.8 EER2 | 13.8 SEER2 + 11.2/9.8 EER2 |
| Split-system heat pump, all regions | 14.3 SEER2 and 7.5 HSPF2 | 14.3 SEER2 and 7.5 HSPF2 |
Heat pump minimums from AHRI’s heat pump summary. 45,000 BTU/h is about 3.75 tons. In the Southeast and Southwest, the rule is based on installation date: a unit that doesn’t meet the 2023 standard can’t be installed there, even if it was built earlier. In the North, it’s based on manufacture date.
How much does a higher SEER2 save?
Cooling electricity scales with the inverse of SEER2. That means you can estimate the savings from an upgrade with simple math:
Savings % = 1 − (old SEER2 ÷ new SEER2)
| Upgrade | Cooling energy saved |
|---|---|
| 13.4 → 15 SEER2 | About 11% |
| 13.4 → 17 SEER2 | About 21% |
| 13.4 → 20 SEER2 | About 33% |
| 15 → 20 SEER2 | About 25% |
To turn that into dollars, multiply by what you spend on cooling each year (not your whole electric bill). For example, if summer cooling costs you $800 a year, going from 13.4 to 17 SEER2 saves roughly $170 a year ($800 × 21%). If the higher-efficiency model costs $1,500 more, that’s a payback of about 9 years. If you only spend $250 a year on cooling, the same upgrade saves around $50 and may never pay back.
These are simplified estimates. Real savings also depend on correct sizing, airflow, refrigerant charge, and duct condition, which can matter as much as the rating itself.
So what rating should you choose?
| Your situation | Reasonable target |
|---|---|
| Hot, long cooling season (South, Southwest) | Above the minimum, often a variable-speed model; check EER2 too |
| Mixed climate, moderate AC use | Mid-range efficiency, compare payback with the math above |
| Short, mild summers | Close to the minimum is usually fine for cooling |
| Heat pump in a cold climate | Prioritize HSPF2 and heating capacity at 5°F over SEER2 |
One more thing to weigh: higher-SEER2 systems usually have variable-speed compressors, which run longer at low speed. That tends to mean quieter operation, more even temperatures, and better humidity control, benefits that don’t show up in the payback math.
Don’t let the rating hide a bad install
A high rating only delivers if the system is installed well. ENERGY STAR lists the essentials of a quality installation: equipment sized from your home’s actual characteristics (not a rule of thumb), airflow that meets the manufacturer’s specifications, the correct refrigerant charge, and a duct inspection with leakage testing. Our guide to choosing an installer lists the questions to ask.
Frequently asked questions
What is a good SEER2 rating?
It depends on your climate. The federal minimum for split-system ACs is 13.4 SEER2 in the North and 14.3 SEER2 in the Southeast and Southwest (under 45,000 BTU/h). In hot climates with long cooling seasons, a higher rating usually pays off faster.
Is SEER2 the same as SEER?
No. SEER2 uses a newer, tougher test that took effect January 1, 2023, so the same unit gets a lower SEER2 number. For example, 13.4 SEER2 is roughly equivalent to 14 SEER.
Can I still install a 14 SEER air conditioner?
In the Southeast and Southwest, systems must meet the 2023 standard on the installation date, so older non-compliant units cannot be installed. In the North, units that met the previous standard and were made before 2023 may still be installed.
How much will a higher SEER2 save me?
Estimate it as 1 minus (old SEER2 divided by new SEER2). Going from 13.4 to 17 SEER2 cuts cooling energy by about 21%. Multiply by your annual cooling cost to see the dollar savings.
What is the minimum SEER2 for a heat pump?
Split-system heat pumps must meet at least 14.3 SEER2 and 7.5 HSPF2 nationwide, according to AHRI.
Sources
- AHRI: Residential Central Air Conditioners (efficiency standards)
- AHRI: Residential Heat Pumps (efficiency standards)
- ENERGY STAR: HVAC Quality Installation
Standards can change. If something here looks out of date, let us know.