Attic Insulation Savings Calculator
Enter your attic area, the R-value you have and the one you'd add, your heating type and the quote, pick your state, and see the heat kept in, the estimated yearly difference and the payback.
Attic insulation savings
G01Scenario A
Sets the electricity rate. Pick US average if you're not sure.
From EIA for US average. Use the rate on your bill if you know it.
Rate used: 18.4¢/kWh · US average · EIA reference 2025–26 · gas $1.55/therm · 4,500 heating degree-days · 1,300 cooling degree-days (data as of 2026-09-26) ·
Estimated savings per year
Payback in US average (climate zone 4): 10.4 years.
- Heat loss avoided (MMBtu per year)
- 11.4
- Heating savings
- $196.70
- Cooling savings
- $43.36
- Savings per year
- $240.06
- Payback
- 10.4 years
Estimate. Formula and sources are under “How it works”. Change any input; the result updates as you type.
2026 note: The federal 25C and 25D tax credits ended for installations after Dec 31, 2025. Our numbers use 2026 rules. State rebates, HEAR/HOMES programs and utility programs may still apply.
Formula
How it works
Heat flows through the attic floor in proportion to 1 ÷ R. More insulation means a higher R and less heat lost in winter (and gained in summer):
- Heat kept in per year (BTU) = area × (1 ÷ R old − 1 ÷ R new) × heating degree-days × 24
- Heating difference = that BTU ÷ 1,000,000 × the cost of 1 million BTU of delivered heat: gas at your state's price per therm and a 90% efficient furnace, or electricity at your state's rate and a heat pump averaging a COP of 2.8
- Cooling difference = area × (1 ÷ R old − 1 ÷ R new) × cooling degree-days × 24, converted to kWh as BTU ÷ (SEER 14 × 1,000) and priced at your rate
- Estimated yearly difference = heating + cooling
- Simple payback = job cost ÷ yearly difference
Recommended attic R-value by IECC climate zone (DOE): zone 1 R-30 · zones 2–3 R-38 · zones 4–8 R-49 to R-60.
Sources: conduction formula U × A × ΔT × time (ASHRAE fundamentals); recommended R-values from DOE and the 2021 IECC; heating and cooling degree-days by state from NOAA 1991–2020 normals; electricity rate from EIA Electric Power Monthly table 5.6.A; natural gas price from EIA.
Worked example
A worked example
Going from R-19 to R-38 over a 2,000 sq ft attic in Texas keeps about 2.5 million BTU a year in the house. With a heat pump, that's worth an estimated $40.99 a year in heating and $40.56 in cooling, $81.54 in total. At $2,200 for the job, the simple payback is 27.0 years. Texas is zone 2, where DOE recommends R-38: this attic is already halfway there, which is why the payback is long.
Reference
By state, at the default inputs
Estimated savings per year, with this page's default inputs and each state's reference prices (EIA reference 2025–26, data as of 2026-09-26).
| US average | $240.06 | 18.4¢/kWh |
|---|---|---|
| Alabama | $210.17 | 15.5¢/kWh |
| Alaska | $366.60 | 25.0¢/kWh |
| Arizona | $178.35 | 15.0¢/kWh |
| Arkansas | $182.50 | 13.0¢/kWh |
| California | $214.36 | 32.0¢/kWh |
| Colorado | $206.43 | 16.0¢/kWh |
| Connecticut | $365.19 | 30.0¢/kWh |
| Delaware | $244.54 | 17.0¢/kWh |
| District of Columbia | $253.02 | 19.0¢/kWh |
| Florida | $141.06 | 15.0¢/kWh |
| Georgia | $181.55 | 14.5¢/kWh |
| Hawaii | $335.02 | 42.0¢/kWh |
| Idaho | $178.79 | 12.0¢/kWh |
| Illinois | $237.55 | 17.0¢/kWh |
| Indiana | $214.22 | 15.5¢/kWh |
| Iowa | $229.86 | 13.5¢/kWh |
| Kansas | $215.40 | 14.5¢/kWh |
| Kentucky | $191.94 | 13.0¢/kWh |
| Louisiana | $139.59 | 12.5¢/kWh |
| Maine | $452.37 | 26.0¢/kWh |
| Maryland | $252.33 | 19.0¢/kWh |
| Massachusetts | $424.09 | 29.0¢/kWh |
| Michigan | $225.95 | 19.5¢/kWh |
| Minnesota | $265.02 | 15.5¢/kWh |
| Mississippi | $156.03 | 13.5¢/kWh |
| Missouri | $226.45 | 13.0¢/kWh |
| Montana | $223.75 | 13.0¢/kWh |
| Nebraska | $216.26 | 12.0¢/kWh |
| Nevada | $186.42 | 15.0¢/kWh |
| New Hampshire | $431.30 | 27.0¢/kWh |
| New Jersey | $237.29 | 22.0¢/kWh |
| New Mexico | $184.71 | 15.0¢/kWh |
| New York | $315.44 | 25.0¢/kWh |
| North Carolina | $214.65 | 14.5¢/kWh |
| North Dakota | $251.54 | 11.5¢/kWh |
| Ohio | $235.89 | 16.5¢/kWh |
| Oklahoma | $197.54 | 13.0¢/kWh |
| Oregon | $215.44 | 14.5¢/kWh |
| Pennsylvania | $267.07 | 18.5¢/kWh |
| Rhode Island | $385.18 | 29.0¢/kWh |
| South Carolina | $189.08 | 15.0¢/kWh |
| South Dakota | $227.54 | 13.0¢/kWh |
| Tennessee | $181.29 | 13.5¢/kWh |
| Texas | $154.81 | 15.5¢/kWh |
| Utah | $180.32 | 12.0¢/kWh |
| Vermont | $419.18 | 22.0¢/kWh |
| Virginia | $208.54 | 15.5¢/kWh |
| Washington | $193.86 | 12.0¢/kWh |
| West Virginia | $201.26 | 15.5¢/kWh |
| Wisconsin | $248.59 | 17.5¢/kWh |
| Wyoming | $215.48 | 12.5¢/kWh |
Questions
FAQ
How much insulation do I need in my attic?
DOE recommends R-30 in zone 1, R-38 in zones 2 and 3, and R-49 to R-60 in zones 4 to 8. The US is zone 4: R-49 to R-60. The result shows your zone next to the estimate.
Does it pay off faster in cold states?
Yes. Heating degree-days drive most of the result. With US-average climate and prices, going from R-11 to R-49 over 1,500 sq ft with a gas furnace is worth about $240.06 a year, a 10.4-year payback on a $2,500 job. In Minnesota, going from R-7 to R-60 over 1,200 sq ft comes to about $379.49 a year and a 7.4-year payback.
Blown-in or batts?
Both reach the same R-value; the calculator only needs the R. Blown-in fills around joists and wires more easily in an existing attic; batts are simpler where the joists are open and regular. Ask for the installed R-value in the quote.
Does attic insulation help in summer?
Yes, more in hot states. In Minnesota the cooling line is small next to the heating line; in Texas the two are about equal. Air sealing the attic floor before insulating matters in both seasons, and this calculator doesn't include it.
Why is my payback so long?
The first inches do most of the work. Going from R-0 to R-11 cuts far more heat loss than going from R-38 to R-60, because heat flow falls with 1 ÷ R. If your attic already has R-19 or more, the next step is worth less.
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