Blown-in Insulation Calculator

Q: How much does blown-in insulation cost?

Blown-in insulation costs $1 to $3 per square foot professionally installed, with most homeowners paying $1,000 to $2,300 for an attic job. A 1,000 sq ft attic blown to R-38 runs $850 to $1,500 installed. DIY runs $0.60 to $1.10 per square foot in materials alone, since you skip the labor to set up and run the machine.

Blown-in insulation costs $1.00 to $3.00 per sq ft installed for a typical attic, with most homeowners paying $1,000 to $2,300 per job. A 1,000 sq ft attic blown to R-38 runs $850 to $1,500 installed, or $650 to $1,050 in DIY materials. Use the calculator to get bags needed, insulation depth, and total cost for your attic.

Estimated total—

Your attic

Attic area

Unit

sq ftm²

Material & R-value

Price assumptions

Bag price ($) Pro installed ($/sq ft)

Defaults & assumptions

Defaults: a 1,000 sq ft attic, cellulose blown to R-38, and US national average rates. Adjust the material, R-value target, and rates above to match your project. The pro installed price assumes a crew brings the machine; DIY assumes you rent a machine for $100 to $200 per day (some stores lend one free with a 20-bag purchase).

Enter your attic area above to see results.

Blown-in insulation cost per square foot

Blown-in insulation is the cheapest way to bring an attic up to code or improve energy efficiency. The biggest line item is labor to set up the machine and feed the hose, which is why pro attic installation averages $1.00 to $2.40 per sq ft but DIY runs only $0.60 to $1.10 per sq ft in materials. Cellulose bags are the cheapest at $15 to $20 and cover about 19 cubic feet; a 30 lb bag of fiberglass runs $30 to $40 but covers about 55 cubic feet, so the two cost about the same per job. Bag count depends on the R-value target: R-38 needs about 12 inches of cellulose, R-49 about 15 inches. The right target for your climate is R-30 in warm southern US, R-38 across the middle band, and R-49 or higher in cold northern climates.

Typical blown-in attic insulation cost (R-38 cellulose, US averages)
Attic size	DIY materials	Professionally installed
500 sq ft	$350 to $550	$450 to $750
1,000 sq ft	$650 to $1,050	$850 to $1,500
1,500 sq ft	$1,000 to $1,600	$1,300 to $2,250
2,000 sq ft	$1,300 to $2,100	$1,700 to $3,000

How the calculator works

Insulation depth = target R-value ÷ R-per-inch of the material. Cubic feet of insulation = attic area × depth in feet (inches ÷ 12). Bags needed = cubic feet ÷ one bag’s coverage, rounded up since you can’t buy a partial bag. Cost is bags times your local bag price for DIY. For pro installed cost, the rate you enter is treated as the price for the selected material at R-38; the calculator scales it by attic area and by how the target depth compares to that R-38 baseline, so a higher R-value costs proportionally more to install. Picking a material prefills its typical rate. Price ranges reflect published US averages from national cost guides (Angi, HomeGuide, 2026).

Blown-in insulation cost FAQ

How much does blown-in insulation cost?

Blown-in insulation costs $1.00 to $3.00 per sq ft professionally installed, with most homeowners paying $1,000 to $2,300 for an attic job. A 1,000 sq ft attic blown to R-38 runs $850 to $1,500 installed. DIY runs $0.60 to $1.10 per sq ft in materials alone, since you skip the labor to set up and run the machine.

How many bags of blown-in insulation do I need?

Divide your attic area in square feet by the coverage per bag (about 17 to 20 sq ft per bag at R-38 for cellulose, depending on bag size). For a 1,000 sq ft attic at R-38 with cellulose, you need about 50 to 60 bags. Add 5 to 10 percent extra for variations in joist depth.

What R-value do I need for my attic?

R-30 for warm southern US (zones 1 to 2), R-38 across the middle band where most US homes sit (zones 3 to 4), and R-49 or higher in cold northern climates (zones 5 to 7). The EnergyStar recommendation is roughly R-38 to R-60 depending on where you live. Going above R-60 is rarely cost-effective for most homes.

Can I install blown-in insulation myself?

Yes. Rent a blowing machine from a home improvement store for $100 to $200 per day (some stores lend one free with a 20-bag purchase), buy 50 to 60 bags of cellulose at $15 to $20 each, and have a helper feed the machine while you run the hose. The bags run $800 to $1,050 for a typical 1,000 sq ft attic at R-38. The main trade-off is the physical work and a few hours of your time versus paying a crew.