Attic insulation calculator
Answer three quick questions. See how many inches of insulation to add, what it should cost installed, and what you'll save each year.
How the attic insulation calculator works
The calculator does three things. First, it compares the insulation in your attic today against the ENERGY STAR target for your climate zone and converts the gap into inches of the material you pick. Second, it prices that gap using the installed cost-per-square-foot ranges from our attic insulation cost guide and blown-in cost data. Third, it estimates annual savings and simple payback from your heating and cooling spend, scaled by how much of the R-value gap the project closes.
Everything runs in your browser and nothing is stored on our servers. When you're ready for quotes, the insulation contractor directory covers state and city pages. Doing HVAC soon? Read why insulation should come before a heat pump.
Attic insulation questions, answered
How much insulation do I need in my attic?
ENERGY STAR recommends R-30 in the warmest climate zone (zone 1), R-49 in zones 2–3, and R-60 across most of zones 4–8. In blown-in cellulose that top target is roughly 17 inches; in blown-in fiberglass it is closer to 24 inches. Many older attics sit at R-11 to R-19 — about 3 to 6 inches — which is the gap this calculator sizes.
How much does attic insulation cost?
Blown-in insulation runs about $1.00 to $2.80 per square foot installed, so a typical 1,000 to 1,500 sq ft attic top-up lands around $1,500 to $3,500. Air sealing the attic first adds roughly $350 to $1,500 for a typical scope, more if the attic has lots of penetrations or old insulation to remove.
Is attic insulation worth it?
Usually, if your attic is under-insulated. EPA and ENERGY STAR put combined air-sealing-plus-insulation savings near 15% of heating and cooling costs, and most projects pay back in 2 to 8 years. It stops being worth it when you already meet the R-value target for your climate — past that point the savings curve flattens fast.
Does attic insulation qualify for a federal tax credit in 2026?
No. The federal 25C credit — 30% back on insulation and air-sealing materials, up to $1,200 a year — ended for work placed in service after December 31, 2025. Plan your payback without it, then check state and utility rebate programs, which in some areas still cover a meaningful share of the job.