Blown-In Insulation Cost Calculator
Calculate blown-in insulation costs by material, area, and R-value target — with federal tax credit and energy savings projections.
How It Works
Enter area and R-value target
Provide the square footage to insulate and your climate zone's target R-value.
Select material type
Cellulose, fiberglass, and mineral wool each have different R-values per inch.
See cost and energy savings
Get total installed cost, federal tax credit amount, and annual energy savings.
Blown-In Insulation Cost by Type
| Type | R-Value/Inch | Cost Per Bag |
|---|---|---|
| Cellulose | R-3.7 | $25 – $40 |
| Fiberglass | R-2.5 | $35 – $55 |
| Rockwool / Mineral Wool | R-3.3 | $45 – $70 |
Frequently Asked Questions
How much does blown-in insulation cost?
Blown-in insulation costs $1.80–$4.50 per sq ft installed depending on type and R-value target. Cellulose insulation to R-38 costs $1.80–$2.80/sq ft. Fiberglass blown-in to R-38 costs $2.00–$3.50/sq ft. A 1,200 sq ft attic costs $2,160–$4,200 installed. DIY is possible with rented machines from home improvement stores at a savings of 40–60% on labor.
Cellulose vs. fiberglass blown-in insulation: which is better?
Cellulose has a higher R-value per inch (R-3.7 vs R-2.5 for fiberglass), resists air movement better, uses 85% recycled content, and is typically 10–15% less expensive. Fiberglass is lighter, doesn't settle as much over time, and is resistant to mold. For most attic applications, cellulose is the better value. For walls where moisture resistance matters more, fiberglass is preferred.
How thick should blown-in insulation be?
Thickness depends on your target R-value and material. For R-49 (recommended for northern US): cellulose needs about 13 inches, fiberglass needs about 20 inches. For R-38: cellulose needs about 10 inches, fiberglass needs about 15 inches. Bags of insulation state the thickness needed per bag for your target R-value — use those charts for accurate ordering.
Is blown-in insulation eligible for a tax credit?
Yes — blown-in insulation qualifies for the federal Energy Efficient Home Improvement Credit: 30% of material costs (not labor) up to $1,200 per year. Both cellulose and fiberglass blown-in insulation qualify when they meet IECC standards. The credit applies to attics, walls, floors over unheated spaces, and rim joists. File IRS Form 5695 with your tax return.
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