SEER to SEER2 Converter
Convert any SEER rating to SEER2 — or SEER2 back to SEER — to compare old and new systems accurately.
The Quick Formula
SEER2 = SEER × 0.9485 for split-system central AC and heat pumps. So SEER 16 ≈ SEER2 15.2. For ductless mini-splits, SEER and SEER2 are the same number. SEER2 was introduced January 2023 — all new systems are now rated in SEER2.
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SEER
Result: SEER2
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SEER2
Common SEER Ratings → SEER2 Equivalents
Click any row to load it into the converter above.
| Description | SEER | SEER2 Equivalent | South Compliant? |
|---|---|---|---|
| Pre-2006 (typical)Many older systems | 10 | 9.5 | ✗ No |
| 2006–2022 (entry)Old federal minimum | 13 | 12.3 | ✗ No |
| 2006–2022 (mid)Mid-range 2010s | 16 | 15.2 | ✓ Yes |
| 2006–2022 (good)Better 2010s units | 18 | 17.1 | ✓ Yes |
| 2023+ entryNew minimum (South) | 14.3 | 13.6 | ✗ No |
| 2023+ midMid-range today | 17 | 16.1 | ✓ Yes |
| 2023+ premiumHigh efficiency today | 21 | 19.9 | ✓ Yes |
2026 Regional SEER2 Minimums
Min SEER2 13.4 (≈ SEER 14.1)
North (CT, IL, IN, ME, MA, MI, MN, NH, NJ, NY, OH, PA, RI, VT, WI)
Min SEER2 14.3 (≈ SEER 15.1)
South & Southwest (AL, AR, AZ, DC, DE, FL, GA, HI, KY, LA, MD, MS, MO, NC, NM, NV, OK, SC, TN, TX, UT, VA, WV)
These are federal minimums for split-system central AC manufactured after January 1, 2023. Contractors cannot legally install new equipment below these thresholds.
Why This Matters When Shopping
If your current system is rated at SEER 16 and a contractor quotes you a new system at SEER2 15.2, you might think you're getting a less efficient system. You're not — SEER2 15.2 and SEER 16 are the same physical efficiency, just measured differently.
Conversely, if you're comparing a quoted SEER2 17 system to your old SEER 16 system, you're getting a genuine 8% efficiency improvement — worth approximately $80–$120/year at average US electricity rates on a 3-ton system.
SEER vs. SEER2 — Common Questions
How do I convert SEER to SEER2?
Multiply SEER by 0.9485 for split-system central AC or heat pumps. SEER2 = SEER × 0.9485. For example: SEER 16 × 0.9485 = SEER2 15.2. For ductless mini-splits, SEER and SEER2 are the same — the factor is 1.0 because mini-splits don't have ductwork.
What is the difference between SEER and SEER2?
Both measure seasonal cooling efficiency, but SEER2 uses more realistic test conditions. SEER tests use 0.1 inches of water column (IWC) external static pressure — essentially no ductwork resistance. SEER2 uses 0.5 IWC, which better simulates actual home ductwork. This makes SEER2 ratings about 4.5–5% lower for the same physical equipment. SEER2 became required for all new equipment on January 1, 2023.
Is SEER 16 the same as SEER2 15?
Nearly identical. SEER 16 converts to SEER2 15.2. If you see SEER2 15 on a new system and your old system was SEER 16, you're getting essentially the same efficiency — not an upgrade, not a downgrade. Make sure the contractor is comparing apples to apples.
Why did SEER change to SEER2?
The Department of Energy updated the testing standard because the old SEER tests were too optimistic. Real-world ductwork creates significantly more resistance than the old 0.1 IWC test pressure assumed. SEER2's 0.5 IWC pressure better reflects how systems actually perform in homes — giving buyers a more accurate picture of real-world efficiency.
What is the minimum SEER2 I can buy in 2026?
13.4 SEER2 in northern states, 14.3 SEER2 in southern and southwestern states. Any new split-system AC or heat pump installed in 2026 must meet or exceed these thresholds. Contractors cannot legally install new equipment below these minimums, even if older non-compliant equipment is still sitting in a warehouse.
Do I need to convert SEER to SEER2 for tax credit purposes?
The federal 25C Energy Efficient Home Improvement Credit expired December 31, 2025 — no federal tax credit applies to 2026 installations regardless of SEER2 rating. For state and utility rebate programs, check requirements at dsireusa.org — these typically specify SEER2 minimums for eligible equipment.
Now calculate what that efficiency difference saves you
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