SEER / SEER2 Converter — Free Online Calculator
Convert an efficiency rating between the old SEER test standard (M1) and the new SEER2 standard (M2, effective January 2023), and compare it against the current federal minimum for your region. The equipment did not change — only the test conditions.
Enter efficiency rating
SEER or SEER2 value from the equipment label
Converted Rating
Federal minimum for your region
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Compliance status
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Conversion factor: SEER2 = SEER × 0.9524 (DOE official M1→M2 factor for split-system AC/heat pumps).
How the SEER / SEER2 Converter Works
DOE published a single conversion factor when it adopted the new M2 test procedure for the 2023 efficiency standards. The physical performance of the equipment is unchanged — the SEER2 number is simply what the same equipment scores on the harder test.
What changed in M2?
The M2 test requires 0.5 in.w.c. external static pressure instead of 0.1 in.w.c. This extra duct resistance reduces measured airflow and cooling capacity, so the same equipment scores about 5% lower in SEER2 vs. SEER.
When to compare SEER vs SEER2
Only compare within the same standard — SEER to SEER, or SEER2 to SEER2. If one quote shows SEER 16 and another shows SEER2 15.2, convert both to the same standard before comparing. SEER 16 = SEER2 15.24, so they are equivalent.
Worked example
A contractor in Texas receives a quote for a 16 SEER unit from an old-stock proposal. Does it meet the 2023 South minimum?
16 SEER (old rating) → SEER2 → compare to South minimum
Result: A 16 SEER unit converts to 15.24 SEER2 and exceeds the 14 SEER2 minimum for Texas. However, if the equipment was manufactured under the old standard and marked "SEER 14" (= SEER2 13.33), it would not meet the South minimum of 14 SEER2.
Frequently asked questions
Common questions about the SEER to SEER2 conversion and 2023 federal efficiency minimums.
Why did SEER change to SEER2?
DOE updated the test procedure in 2023 to require testing at a higher external static pressure (0.5 in.w.c. vs. 0.1 in.w.c.). The new M2 test better reflects real-world duct resistance. A SEER2 14 unit performs identically to the old SEER 14.7 unit — it is the same equipment, tested differently.
What is the exact SEER to SEER2 conversion factor?
DOE published a conversion factor of 0.9524 for split-system central air conditioners and heat pumps. So SEER2 = SEER ÷ 1.05. Some manufacturers round slightly. This calculator uses the official DOE factor.
Does the new minimum mean new equipment is less efficient?
No. The SEER2 14 minimum represents the same physical efficiency as the old SEER 14.7 minimum. Consumers should compare SEER2 to SEER2 (both new standard) or SEER to SEER (both old standard) — never mix the two.
Does this conversion apply to heat pumps?
Yes, with the same 0.9524 factor for the cooling SEER/SEER2 rating. Heat pump heating efficiency uses a separate conversion: HSPF2 = HSPF × 0.851. The heat pump federal minimum is 14.3 SEER2 (all regions) effective January 2023.
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