Maintained by the BuildSolver engineering team · Updated
Calculator · Energy cost
SEER2 energy cost calculator
Enter the cooling capacity and both units' SEER2 ratings. Add the full-load equivalent cooling hours the job runs in a year and the local electricity price, and the calculator returns the annual electricity use and cost for each unit. Enter the price gap between the two pieces of equipment as well, and it adds a payback period.
- Tons of cooling capacity for the equipment being compared, 1 to 5 tons in half-ton steps.
- The existing unit's SEER2 (or its closest AHRI-listed equivalent) and the new unit's SEER2 from its nameplate or the AHRI Certified Directory.
- Full-load equivalent cooling hours per year for the climate, and the local $/kWh rate (defaults to the latest U.S. average from the EIA).
- The result updates as you type and shows both units' annual electricity use and cost, the savings, and a payback period if you enter a price difference.
Example result for the default inputs
3 tons at 1,500 full-load hours per year, $0.1834/kWh.
Annual savings
$338.81 saved per year
New unit annual cost
$651.55 per year
| Cooling capacity | 3 tons (36,000 BTU/h) |
|---|---|
| Full-load equivalent hours | 1,500 h/yr |
| Electricity price | $0.1834/kWh |
| Existing unit, SEER2 | 10 |
| Existing unit, annual electricity use | 5,400 kWh |
| Existing unit, annual cost | $990.36 |
| New unit, SEER2 | 15.2 |
| New unit, annual electricity use | 3,553 kWh |
| New unit, annual cost | $651.55 |
For estimation purposes only. Consult a licensed engineer for final designs.
Free without signup, 3 questions a day
How the SEER2 cost comparison is calculated
SEER2 is defined as total cooling output in BTU divided by total electric energy input in watt-hours over a cooling season (DOE 10 CFR 430 Subpart B Appendix M1). Turning that around for a capacity and a run time gives the annual electricity use directly. Multiplying by the local electricity price gives the annual cost.
- Annual electricity use
kWh/yr = capacity (BTU/h) x hours / SEER2 / 1,000kWh per year = tons x 12,000 x full-load hours / SEER2 / 1,000.- Annual cost
Cost = kWh/yr x $/kWhAnnual kWh times the $/kWh rate. The default rate is the EIA Electric Power Monthly national residential average, so swap in the rate from the customer's utility bill before you quote.- Annual savings
Savings = existing unit cost - new unit costNegative when the new unit's SEER2 is lower than the existing unit's. The result then shows the difference as a cost increase, more per year, with a warning.- Simple payback
Years = price difference / annual savingsShown when a price difference is entered. A new unit that costs less and saves money pays back immediately, and with no annual savings there is nothing to pay back. It ignores financing cost, maintenance, refrigerant, rebates and future electricity price changes.
Worked example, a 3-ton change-out from 10 to 15.2 SEER2
A 3-ton system runs 1,500 full-load equivalent hours a year at $0.1834 per kWh, the U.S. average residential rate for June 2026 (EIA Electric Power Monthly, Table 5.6.A). Replacing a 10 SEER2 unit with a 15.2 SEER2 unit at the same capacity and duty cycle drops the annual cooling bill from $990.36 to $651.55.
3 tons · 10 SEER2, existing
$990.36 per year
3 tons · 15.2 SEER2, new
$651.55 per year
That is $338.81 a year in savings. Add a $1,500 installed-price difference between the two units and the payback comes to 4.4 years, ignoring financing, maintenance and any rebate.
Standards and data sources
- DOE 10 CFR 430, Subpart B, Appendix M1 - the SEER2 test procedure, effective January 1, 2023, and its definition of SEER2 as BTU cooling output per watt-hour of electric input.
- AHRI Standard 210/240-2023 - the industry test standard that implements Appendix M1 for unitary air conditioners and heat pumps, and backs the AHRI Certified Directory ratings.
- DOE regional minimum efficiency standards, 10 CFR 430.32(c) - the 13.4 SEER2 North and 14.3 SEER2 Southeast/Southwest minimums for split-system central air conditioners under 45,000 BTU/h, effective January 1, 2023.
- EIA Electric Power Monthly, Table 5.6.A - the default U.S. average residential electricity price, updated from the June 2026 data release.
Limitations of this calculator
- Full-load equivalent hours usually drive the biggest swing in the answer, more than the SEER2 numbers themselves. A wrong guess there overwhelms a precise SEER2 comparison. Use utility bill history or a load calculation when you can.
- Equipment before 2023 carries a SEER rating from the older, lower-static-pressure test procedure. Entering that SEER number as if it were SEER2 can overstate the old unit's efficiency by an amount that depends on the specific equipment. No single published conversion factor corrects for it.
- A fixed full-load-hours figure treats the whole season as one duty cycle. Variable-speed equipment runs at part load for much of the season, and SEER2 already blends part-load and full-load test points under DOE Appendix M1, so a single full-load-hours figure can misstate its real use. Treat the result for that equipment as a ballpark and use a bin-hour energy model when the customer needs a firmer number.
- This calculator prices cooling electricity only. It does not include installation, maintenance, refrigerant, financing, rebates, or heating-side energy use for a heat pump.
- Electricity prices vary by utility, rate schedule and season, and time-of-use and demand charges are not modeled.
- Whole-house Manual J and the formula calculators on this site are free. Room-by-room load allocation and full Manual S equipment selection are part of the Pro plan.
Common SEER2 comparison mistakes
- Comparing an old SEER nameplate directly against a new SEER2 nameplate. The two numbers come from different test conditions. Look up the AHRI Certified Directory rating where possible. If you can't find one, tell the customer the old unit's number is an estimate.
- Every climate needs its own full-load hours figure. A house in Phoenix and a house in Seattle do not run anywhere near the same number of full-load cooling hours.
- Oversizing the new unit because higher SEER2 sounds like more savings. An oversized unit short-cycles, which ACCA Manual S sizing limits exist to prevent, and gives back part of its rated efficiency along with the humidity complaints you already know about. Check the load with the AC sizing calculator or a full Manual J before quoting the SEER2 upgrade.
- Quoting payback off equipment list price. Use the installed price difference between the two options, or the payback number means nothing to the customer.
- When the new unit's SEER2 is lower. If a proposed unit's SEER2 is lower than the one being replaced, the calculator shows a higher annual cost for the new unit. Use it to catch a quote that pairs the job with the wrong equipment.
Common questions about SEER2 energy cost
What is SEER2 and how is it different from SEER?
SEER2 is the cooling efficiency rating defined by the DOE test procedure in 10 CFR 430 Subpart B Appendix M1, effective January 1, 2023. It replaced the older SEER test (Appendix M), whose minimum external static pressure stepped up with capacity (0.10 inches of water column up to 28,800 BTU/h, 0.15 inches for 29,000 to 42,500 BTU/h, 0.20 inches from 43,000 BTU/h up). M1 tests conventional ducted systems at a flat 0.50 inches of water column, closer to what a real ducted system sees. Both ratings are BTU of cooling output per watt-hour of electricity input, measured under different test conditions.
Can I convert a SEER rating to SEER2 with a fixed factor?
Not reliably. Manufacturers requalified individual models under the new test one at a time, so the gap between a unit's SEER and SEER2 rating depends on its specific design and airflow. Check the AHRI Certified Directory for the model's actual SEER2 rating.
What are the minimum SEER2 requirements after 2023?
For split-system central air conditioners under 45,000 BTU/h, the DOE regional minimums are 13.4 SEER2 in the North region and 14.3 SEER2 in the Southeast and Southwest regions. Larger split systems and single-package units have their own minimums. Check the equipment's region and capacity before assuming a number.
Where does the default electricity price come from?
$0.1834 per kWh, the U.S. average residential price for June 2026 from the EIA Electric Power Monthly, Table 5.6.A. Replace it with the number on the customer's actual utility bill for a real quote. Rates vary widely by state and utility.
What full-load equivalent hours should I enter?
There is no single correct national number, since it depends on the climate and how the house runs. As a starting point, check the customer's summer utility bills against the equipment's rated capacity, or run a load calculation for the house.
Why does the calculator show a cost increase for some inputs?
If the new unit's SEER2 is equal to or lower than the existing unit's, running the new unit costs the same or more. The result then shows the dollar difference as more per year, or no change, and adds a warning.
Why is there no payback period showing?
Payback only appears once you enter the equipment price difference. If the annual savings are zero or negative, payback shows "not applicable", since nothing pays back. If the new unit costs no more up front and also saves money, payback shows as immediate.
Does a higher SEER2 unit always cost less to run?
At the same capacity and duty cycle, yes. An oversized high-SEER2 unit that short-cycles can give back part of that rated efficiency, so size the equipment to the load first and then compare SEER2 options for that size.
Used on the same job
Open the chat with the job's numbers
The chat has no energy cost tool, so the SEER2 comparison stays on this page. Before you compare options, describe the house in chat and the assistant runs the free whole-house load, which tells you whether the tonnage you are pricing fits the house.
Open the chat