SEER2 Explained
What changed in 2023, how SEER converts to SEER2, and the regional minimums.
9 min
SEER2 savings calculator
Efficiency upgrades are sold in percentages and bought in dollars. Put in your tonnage, your run hours and your power price, and the tool prints both — plus the payback on the upcharge.
Pre-filled with a 3-ton system, 1,200 equivalent full-load cooling hours, and a 10 SEER unit replaced by a 16 SEER2 one.
tons
h/yr
About 600 in Seattle, 1,200 in St. Louis, 2,400 in Phoenix.
SEER
SEER2
¢/kWh
$
$297
Saved per year
Pays the upcharge back in 4.7 years.
| Energy | Cost | |
|---|---|---|
| Existing at 10 SEER | 4,320 kWh | $792 |
| New at 16 SEER2 | 2,700 kWh | $495 |
| Difference | 1,620 kWh | $297 |
The arithmetic
SEER and SEER2 are both BTU of cooling delivered per watt-hour of electricity consumed, averaged over a season. So the energy a system uses is capacity × hours ÷ rating:
kWh/yr = (tons × 12,000 × full-load hours) ÷ (SEER2 × 1,000)
Because the rating is in the denominator, the savings curve flattens fast. Going from 10 to 14 cuts energy by 29%. Going from 14 to 18 cuts it by a further 22%, but you are cutting 22% of a much smaller number — and paying for it with the same kind of upcharge.
Diminishing returns, in numbers
| Rating | kWh/yr | Cost at 18.34¢ | Saved vs 10 SEER |
|---|---|---|---|
| 10 SEER | 4,320 | $792 | — |
| 13.4 SEER2 | 3,224 | $591 | $201 |
| 15 SEER2 | 2,880 | $528 | $264 |
| 16 SEER2 | 2,700 | $495 | $297 |
| 18 SEER2 | 2,400 | $440 | $352 |
| 20 SEER2 | 2,160 | $396 | $396 |
The jump from the federal minimum to 20 SEER2 is worth about $195 a year in this example. If the upcharge is $3,000 that is a fifteen-year payback on equipment that may not last that long. In Phoenix, at twice the run hours, the same upgrade pays back in seven.
SEER against SEER2
Do not compare the two numbers directly
SEER2 is the same measurement taken under a higher external static pressure — 0.5 in. w.c. instead of 0.1 — which is closer to a real duct system. The same machine scores roughly 4.5% lower on SEER2 than it did on SEER. A 16 SEER unit is about 15.2 SEER2. If you are comparing a 2020 quote with a 2026 one, convert first; the SEER2 guide has the conversion.
What the tool leaves out
Three things, deliberately. It prices cooling only, because heating is a different rating and a different fuel. It ignores utility rebates, which move fast and vary by territory — check yours before you decide. And it assumes the duct system can deliver the airflow a high-efficiency unit needs; a variable-speed condenser on a duct system reading 0.9 in. w.c. of static will not hit its rating. Measure that first with the static pressure calculator.
Sources: 10 CFR 430.32(c)(5)(i) (read 2026-09-04) · EIA Electric Power Monthly, Table 5.6.A (released 2026-08-26) (read 2026-09-04)
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