Blow-in Insulation Cost Calculator
Estimated Total Cost
$1,120 – $1,963
$1.12 – $1.96 per sq ft
Material
$570 – $1,013
Labor
$550 – $950
Bags Needed
51 bags
Installed Depth
15.2"
Depth Guide: R-38 with blown-in fiberglass requires 15.2 inches of insulation (R-2.5 per inch).
Disclaimer: Estimates are for budgeting purposes only. Actual costs vary by location, contractor, material availability, and project complexity. Always get professional quotes for exact pricing.
Blow-in Insulation Cost Breakdown
| Insulation Type | Material / Sq Ft | Labor / Sq Ft | Total / Sq Ft | R-Value / Inch |
|---|---|---|---|---|
| Blown-in Fiberglass | $0.45 – $0.80 | $0.55 – $0.95 | $1.00 – $1.75 | R-2.5 |
| Blown-in Cellulose | $0.50 – $0.85 | $0.55 – $0.95 | $1.05 – $1.80 | R-3.5 |
| Mineral Wool (Rockwool) | $0.70 – $1.20 | $0.80 – $1.30 | $1.50 – $2.50 | R-3.3 |
Average Project Costs (Cellulose, Attic)
| Project | Area | R-Value | Bags | Estimated Total |
|---|---|---|---|---|
| Small Attic | 500 sq ft | R-38 | 16 bags | $592 – $1,013 |
| Standard Attic | 1,000 sq ft | R-38 | 32 bags | $1,183 – $2,027 |
| Large Attic | 1,500 sq ft | R-49 | 62 bags | $2,050 – $3,508 |
| Extra-Large Attic | 2,000 sq ft | R-38 | 64 bags | $2,367 – $4,053 |
How We Calculate
Our blow-in insulation calculator estimates project costs using coverage area and target R-value as the base inputs. Material costs scale with R-value (more insulation depth = more material), while labor costs depend on the application area.
How the math works: We start with a base material cost per square foot at R-30 and multiply by an R-value factor (target R-value ÷ 30). Labor cost uses a flat per-square-foot rate multiplied by an application factor: 1.0× for attic open blow, 1.3× for floor/crawlspace, and 1.5× for wall dense-pack. Bags are calculated as: area × target R-value ÷ (bags coverage at R-30 × 30). Installed depth = target R-value ÷ R-value per inch.
Insulation Types Comparison
Blown-in Fiberglass ($1.00–$1.75/sq ft at R-30) is lightweight and moisture-resistant. At R-2.5 per inch, it requires the most depth to reach a given R-value. It doesn’t settle significantly and won’t absorb water. Best for humid climates and areas prone to moisture.
Blown-in Cellulose ($1.05–$1.80/sq ft at R-30) is made from recycled newspaper treated with borate fire retardant. At R-3.5 per inch, it’s denser and provides better air sealing than fiberglass. The most popular choice for attic retrofits. Settles 10–20% initially, so installers over-blow to compensate.
Mineral Wool / Rockwool ($1.50–$2.50/sq ft at R-30) offers R-3.3 per inch with superior fire resistance and sound dampening. It’s the premium option, costing 50–75% more than fiberglass or cellulose. Best for applications where fire resistance or soundproofing is a priority.
R-Value Targets
The target R-value determines how much insulation you need. R-19 is standard for wall cavities (2×6 walls). R-30 is the baseline for attic insulation. R-38 is the most common recommendation for attics in climate zones 4–8. R-49 to R-60 is recommended for cold climates (zones 5–8) and Energy Star compliance. Higher R-values increase material cost proportionally.
Application Area Factors
Attic open blow is the simplest and cheapest application — the insulation is blown directly over the attic floor. Wall dense-pack requires drilling 2–3” holes in each stud bay, blowing insulation to high density, and patching the holes — adding 50% to labor costs. Floor and crawlspace work adds 30% due to access difficulty and working in confined spaces.
Additional Cost Factors
Our estimates cover insulation material and installation labor but do not include air sealing ($200–$600, recommended before insulating), old insulation removal ($1–$2/sq ft if needed), attic baffles/vents ($2–$4 each), or drywall patching for wall dense-pack ($2–$5/hole). Many contractors offer air sealing as a package with insulation.
Data Sources
Pricing data is compiled from HomeAdvisor, Angi, RSMeans, EnergyStar.gov, and verified insulation contractor estimates across multiple US regions. R-value specifications follow DOE and manufacturer guidelines. We review and update this data regularly.
Last updated: 2026-02-02
Frequently Asked Questions
How much does blow-in insulation cost? +
Blow-in insulation costs $1.00–$2.50 per square foot installed, depending on material and R-value. Fiberglass runs $1.00–$1.75/sq ft, cellulose $1.05–$1.80/sq ft, and mineral wool $1.50–$2.50/sq ft at R-30. Higher R-values increase material cost proportionally. A standard 1,000 sq ft attic insulated to R-38 with cellulose costs $1,183–$2,027.
Is cellulose or fiberglass blow-in insulation better? +
Both are excellent choices. Cellulose (R-3.5/inch) is denser, better at air sealing, and made from recycled material — it needs less depth to reach the same R-value. Fiberglass (R-2.5/inch) is lighter, doesn’t absorb moisture, and won’t settle as much over time. Cellulose is slightly more expensive but is often preferred for its superior air-sealing properties.
What R-value do I need for my attic? +
The Department of Energy recommends R-38 to R-60 for attics in most US climate zones. R-38 is the minimum recommendation for zones 4–8 (most of the US). R-49 to R-60 is recommended for cold climates (zones 5–8). Check your local building code — many jurisdictions require R-38 minimum for new construction and major renovations.
How many bags of blow-in insulation do I need? +
Bag count depends on area, R-value target, and insulation type. At R-30: fiberglass covers about 25 sq ft per bag, cellulose covers about 40 sq ft per bag, and mineral wool covers about 20 sq ft per bag. For higher R-values, each bag covers proportionally less area. Our calculator computes the exact bag count for your project.
Can I blow in insulation myself? +
Yes, attic blow-in insulation is a popular DIY project. Many home improvement stores offer free blower machine rental with a minimum bag purchase (typically 10–20 bags). DIY saves $0.50–$1.00/sq ft in labor costs. However, wall dense-pack insulation requires specialized equipment and technique — that’s best left to professionals.
How long does blown-in insulation last? +
Blown-in insulation lasts 20–30+ years when properly installed. Fiberglass maintains its R-value indefinitely and doesn’t settle significantly. Cellulose can settle 10–20% over the first few years, so installers typically over-blow by 10–15% to compensate. Neither material degrades chemically — the main enemies are moisture damage and pest disturbance.
Does blown-in insulation settle over time? +
Cellulose insulation settles about 10–20% in the first 1–2 years after installation. Professional installers account for this by blowing in 10–15% extra material. Fiberglass blow-in settles minimally (less than 5%). Both types maintain their R-value well after initial settling. If your existing insulation has settled significantly, adding a top-up layer is a cost-effective solution.
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