SEER Savings Calculator: Is a Higher SEER2 Worth It?

A higher SEER2 rating means the air conditioner or heat pump uses less electricity for the same cooling. Whether that’s worth paying for depends on two things that vary a lot by state: how many hours your AC runs, and what you pay for electricity. This calculator estimates both from public data, compares your current unit with a new one, and shows the yearly savings and the payback.

How it works

full-load hours = 24 × cooling degree days ÷ (design temperature − 65 °F)
kWh per year    = tons × 12,000 × full-load hours ÷ (SEER2 × 1,000)
cost per year   = kWh × electricity price
payback (years) = extra cost ÷ yearly savings

Full-load hours are how long the unit would run at full capacity to deliver a season’s cooling. We estimate them from NOAA’s 1991–2020 cooling degree days for your state and the cooling design temperature from NOAA hourly normals. The formula assumes the unit is sized to the design load and that cooling demand rises with degree days. It’s a planning estimate. Your thermostat setting, sun, humidity and how well the unit is sized will move it.

SEER and SEER2. Labels on units made before 2023 show SEER. The new SEER2 test uses more realistic duct pressure, so the same unit rates about 5% lower. If your current unit has an older SEER label, the calculator converts it at SEER2 ≈ 0.95 × SEER so both sides compare fairly.

Electricity price defaults to your state’s average residential price from the EIA. Enter your own rate if you have it, including delivery charges.

What it doesn’t count: heating savings from a more efficient heat pump, the age-related efficiency loss of an old unit, and maintenance. Each of those usually favors the new unit.

Worked example

A Houston-area homeowner has a 3.5-ton air conditioner from 2005 rated 10 SEER. A 16 SEER2 replacement costs $1,800 more than the 14.3 SEER2 minimum unit. Texas has 2,809 cooling degree days a year, a 99 °F design temperature, and an average residential price of 16.03¢ per kWh.

• Full-load hours: 24 × 2,809 ÷ (99 − 65) = 1,983 hours
• Old unit: 10 SEER ≈ 9.5 SEER2. 3.5 × 12,000 × 1,983 ÷ 9,500 = 8,766 kWh, or about $1,405 a year
• New 16 SEER2 unit: 5,205 kWh, about $834 a year, so it saves $571 a year against the old one
• Compared with the 14.3 SEER2 minimum unit, a 17 SEER2 unit saves about $148 a year, so $1,800 extra pays back in about 12 years

The big saving comes from replacing a 20-year-old unit. The step from the minimum efficiency to a higher one is smaller. It’s still worth it in Texas over a 15-year life, but barely. In Minneapolis, with 456 cooling degree days, the same step up saves about $28 a year on a 3-ton unit.

SEER2 savings by state: reference table

Yearly cooling cost per ton at the federal minimum (13.4 SEER2) and at 17 SEER2, using each state’s average electricity price. Multiply by your system size in tons.

Tips and common mistakes

Use your real electricity rate. Divide the total on your bill (energy plus delivery) by the kWh used. Summer rates and time-of-use plans can be well above the state average.

Size first, then pick efficiency. An oversized high-SEER2 unit short-cycles and loses much of its advantage. Run the AC size calculator before you compare efficiency levels.

Look at variable speed for humidity. In humid climates, variable-speed systems run longer at low speed and pull more moisture out of the air, which a SEER2 number doesn’t capture.

Fix ducts and filters. Leaky ducts in a hot attic and dirty filters can cut real-world efficiency more than the gap between two SEER2 levels.

Count the heating side for heat pumps. If you’re comparing heat pumps, the HSPF2 heating rating matters as much as SEER2 in most of the country.