Blown in Insulation Cost Calculator
Square footage, material, and R-value target in — total installed cost out for attic or wall projects.
This blown-in insulation cost calculator estimates material and labor costs for fiberglass and cellulose loose-fill insulation based on area, R-value target, and application location, and compares total cost and long-term savings against standard batt insulation.
The national average for blown-in insulation cost runs $1.00–$2.80 per square foot installed. That range covers two materials — cellulose and fiberglass — across different R-value targets and locations. Attic work costs less per square foot than walls. Cellulose and fiberglass price similarly, but cellulose needs less depth to hit the same R-value. Where your project lands depends on which combination of those variables applies.
Blown-In Insulation Cost Per Square Foot
| Material | Cost Per Sq Ft (Installed) | R-Value Per Inch |
|---|---|---|
| Blown-in cellulose | $1.10–$2.80 | 3.2–3.8 |
| Blown-in fiberglass | $1.00–$2.50 | 2.2–2.7 |
| Dense-pack cellulose (walls) | $1.60–$4.20 | 3.5–3.8 |
How Much Does Blown-In Attic Insulation Cost?
Most homeowners pay $900–$3,600 for blown-in attic insulation, with the typical project landing at $1,500–$2,500 for a 1,000–1,200 sq ft attic brought to R-38. The DOE recommends R-38 to R-60 depending on your climate zone — colder zones like Minnesota and Maine need R-49 to R-60; warmer Southern zones need R-30 to R-38.
| Attic Size | R-38 (Cellulose) | R-38 (Fiberglass) | R-49 (Cellulose) |
|---|---|---|---|
| 800 sq ft | $880–$1,600 | $800–$1,500 | $1,400–$2,400 |
| 1,000 sq ft | $1,100–$2,000 | $1,000–$1,900 | $1,800–$3,000 |
| 1,200 sq ft | $1,320–$2,400 | $1,200–$2,200 | $2,200–$3,800 |
| 1,500 sq ft | $1,650–$3,000 | $1,500–$2,750 | $2,700–$4,500 |
Cost of Blown-In Insulation in Walls
Wall insulation costs more than attic work. In existing homes, installers drill small holes between studs, inject dense-pack cellulose or fiberglass, then patch and paint. The cost of blown-in insulation in existing walls runs $1.70–$4.20 per square foot — higher than attic rates because of drilling, patching, and painting labor. New construction is cheaper since wall cavities are open before drywall.
What R-Value Do You Need — and How It Affects Cost
R-value is the most direct cost driver — more depth means more material and higher cost per square foot. DOE recommendations by climate zone:
- Zones 1–2 (Florida, South Texas, Hawaii): R-30 to R-38
- Zones 3–4 (Southeast, Mid-Atlantic, Pacific Northwest): R-38 to R-49
- Zones 5–6 (Midwest, New England, Mountain West): R-49 to R-60
- Zones 7–8 (Northern Minnesota, Alaska): R-60+
Most pre-1980 homes have R-11 to R-19 in the attic — well below current recommendations. Topping up to R-49 is one of the highest-ROI home improvement projects available, typically cutting heating and cooling costs 10–20%.
Cellulose vs. Fiberglass Blown-In Insulation
Cellulose delivers R-3.2 to R-3.8 per inch; fiberglass delivers R-2.2 to R-2.7. Cellulose needs less depth to hit the same R-value, which reduces total material cost on deep attic installs. Fiberglass handles moisture better and is preferred in humid Southern climates. Both materials are blown with the same equipment at similar labor rates — the choice usually comes down to climate zone and moisture exposure.
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Blown-in cellulose runs $1.10–$2.80 per square foot installed; blown-in fiberglass runs $1.00–$2.50. Dense-pack cellulose for existing walls costs $1.60–$4.20 per square foot due to the added labor for drilling and patching. The final rate depends on material type, R-value target, and whether the work is in an open attic or existing wall cavities.
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Most homeowners pay $900–$3,600. A standard 1,000–1,200 sq ft attic brought to R-38 costs $1,100–$2,400 for cellulose or $1,000–$2,200 for fiberglass installed. Reaching R-49 adds $700–$1,600 to the total. Contaminated existing insulation removal adds $1.00–$2.00 per sq ft if needed.
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Cellulose delivers more R-value per inch (R-3.2 to R-3.8 vs. R-2.2 to R-2.7 for fiberglass), meaning less depth is needed to hit the same target — reducing material cost on deep attic installs. Fiberglass resists moisture better and is preferred in humid Southern climates. For most Northern and Midwestern attics, cellulose is the better value.
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Blown-in insulation for existing walls runs $1.70–$4.20 per square foot — more expensive than attic work because installers drill holes between studs, inject dense-pack material, then patch and paint. For a typical home with 300–500 sq ft of exterior wall cavity, total cost runs $500–$2,100 for insulation alone, not including paint touch-up.