Blown-In Insulation Cost Calculator
Blown-in insulation is priced two very different ways. In an open attic it is sold by the bag and blown loose to a depth; in finished walls it is dense-packed through holes drilled in each cavity. Pick where it is going and this prices the bags, the labor and the patching.
Your project
Ignored for walls — a wall is filled to its full cavity depth.
Your results
- Installed blown-in cost
- $2,124 – $3,372
- Cost per sq ft
- $1.77 – $2.81
- Bags
- 108 bags
- Includes 10% for settling and obstructions
- Settled depth
- 13.6 in for R-49
- Material
- $1,404 – $2,052
- Labor
- $720 – $1,320
Estimates use typical US material and labor pricing. Confirm quantities against the coverage chart on the bag before you buy.
Gear for this job
Blown In Cellulose Insulation
Attic Measuring Rulers - Attic Insulation R-Value Ruler,Thick Card Stock,25 inches,for Ceiling Insulators Insulation (30)
$26.99
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Aimee’s Workshop Attic Anchor - Insulation Ruler Depth Markers for Blown-in Insulation 30 Pack, 24 Inch Heavy Cardstock
$29.98
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Attic Insulation R-Value Ruler - Attic Measuring Rulers, 25 Inch Colorful Card Stock Attic Depth Ruler for Home,(100 per Pack (100)
$42.99
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Insulation Blower Machine Rental
Pangda 10 Pack Insulation Removal Vacuum Bags Heavy Duty 75 Cu ft,Black
$95.99
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(10) Insulation Vacuum Bag RAM Heavy Duty ECO+ Bags 7 FT X 4 FT Holds 88 CF / 400 LBS Low DUST 2.4 Fabric Strength - 10 Pack. Largest and Toughest Green Bag on The Market.
$132.94
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RAM (10) Insulation Removal Vacuum Bag - Super Heavy Duty Tear-Proof 6 FT X 4 FT - Easy-Fill SPOUT & Lowest DUST Filter - Contractors #1 Choice - EST 450 LBS / 75 CF PRO-450 (3.5 oz Strength)
$151.06
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Respirator Mask Insulation Work
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Prices as of Oct 1, 2026, 4:38 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
How this calculator works
- Attic bags = R to add × area ÷ bag rating × 1.10
- Wall cavity volume = wall area × 0.88 (framing) × stud depth
- Wall bags = cavity volume × dense-pack density ÷ bag weight × 1.10
- Pro walls = wall area × $1.40–$3.40 per sq ft installed, + patching if drilled inside
Blown-in attic cost at R-49 by attic size (cellulose, contractor)
| Attic | Bags | Installed cost |
|---|---|---|
| 800 sq ft | 72 | $1,416 – $2,248 |
| 1,000 sq ft | 90 | $1,770 – $2,810 |
| 1,200 sq ft | 108 | $2,124 – $3,372 |
| 1,500 sq ft | 135 | $2,655 – $4,215 |
| 2,000 sq ft | 180 | $3,540 – $5,620 |
Adding R-49 over a bare attic floor. Air sealing and old-insulation removal are priced separately in the attic insulation cost calculator.
Dense-pack wall R-values
| Material | 2×4 wall (3.5 in) | 2×6 wall (5.5 in) |
|---|---|---|
| Blown-in fiberglass | R-14 | R-22 |
| Blown-in cellulose | R-13 | R-20 |
| Blown-in mineral wool | R-13 | R-21 |
Cavity R-value only; studs conduct heat, so the whole-wall figure is lower.
Fiberglass or cellulose?
In an attic both work, and contractors charge similar prices for either. Cellulose is denser, resists air movement better and gets more R per inch; fiberglass is lighter, does not absorb water and settles less. The bigger price difference is DIY: cellulose bags are cheaper, but you need more of them, so compare the bag counts above rather than the shelf price.
In closed walls, dense-pack cellulose is the usual choice because packing it to about 3.5 lb per cubic foot stops it settling and blocks air flow through the cavity. It needs a high-pressure blower and a fill tube — the free machines lent with bag purchases are built for loose attic fill and will not dense-pack a wall.
Drill-and-fill: what to expect
Installers either remove a course of siding or drill through it and plug the holes, or drill 1–2 inch holes from inside and patch them. From inside, budget for patching and repainting every wall. Before any wall is filled, check for knob-and-tube wiring, which should not be buried in insulation, and for signs of water getting into the wall.
2026 cost guides put contractor dense-pack cellulose in walls at roughly $1.50–$3.00 per square foot of wall, with some regional quotes up to about $4 — the default range here is $1.40–$3.40 depending on material. Attic blown-in runs roughly $1.00–$1.80 per square foot installed in the same guides.
Sources consulted: Angi, HomeGuide and HomeAdvisor blown-in insulation cost guides (2026 data); manufacturer coverage charts for loose-fill cellulose and fiberglass.
Frequently asked questions
How much does blown-in insulation cost per square foot?
Adding R-49 to a bare attic floor is roughly $1.60–$2.50 per square foot installed in this calculator for fiberglass and $1.80–$2.80 for cellulose at retail bag prices (contractors buying in bulk often land lower), and about $1.00–$1.80 DIY. Published averages of $1.00–$1.80 usually assume a smaller top-up. Dense-packing closed walls is about $1.40–$3.40 per square foot of wall with a contractor.
How many bags of blown-in insulation do I need?
Multiply the R-value you are adding by the area and divide by the bag's rating: about 600 R·sq ft per 19 lb bag of GreenFiber-style cellulose (its chart: 12 sq ft per bag at R-49) and about 1,950 for AttiCat-style fiberglass. 1,000 sq ft at R-49 is roughly 90 bags of cellulose or 28 of fiberglass, with 10% extra.
Can you blow insulation into existing walls?
Yes — that is drill-and-fill. Holes are drilled into each stud bay from outside or inside, and cellulose or fiberglass is dense-packed through a fill tube. Fire blocks and horizontal framing mean some bays need a second hole.
Is blown-in insulation DIY-friendly?
In an open attic, yes — with a helper feeding the machine, a mask, and baffles installed at the eaves first. Dense-packing walls is harder to do well, and poorly packed walls settle and leave cold gaps at the top.
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Installed blown-in cost
$2,124 – $3,372