Enter 0 for new installs. For top-ups, estimate existing R-value (e.g., R-11 for old 3.5" batts).
Blown-In Insulation Estimate
Installation Details
Cost Breakdown
Estimated Total Cost
$1,719
Blown-In Cellulose, R-38 added, 1,000 sq ft
12,800+ estimates calculated this month
- Attic: R-38 to R-60 (cold climates need R-49+)
- Walls (dense pack): R-13 to R-21
- Floor / Crawlspace: R-19 to R-30
Source: DOE / IECC 2021 residential energy code
Last updated: 2026-04-04
How Much Does Blown-In Insulation Cost?
Installed blown-in insulation runs $1.00 to $3.00 per square foot depending on the material, depth, and your location. For a typical 1,000 sq ft attic blown to R-38, expect to pay $1,500 to $2,500 with professional installation. DIY jobs can cut that by 40-50% since blown-in cellulose and fiberglass are among the most DIY-friendly insulation options.
I've seen plenty of homeowners overpay on insulation because they didn't know the target R-value for their climate zone, or because they didn't account for the insulation already in the attic. If you've got R-19 up there already, you don't need to start from scratch. Top it up to R-38 or R-49 and you're in good shape.
Blown-In Insulation Cost by Material (2026)
| Material | R-Value/Inch | Installed $/Sq Ft | 1,000 Sq Ft (R-38) |
|---|---|---|---|
| Cellulose | R-3.5 | $1.00 - $2.50 | $1,500 - $2,200 |
| Fiberglass | R-2.5 | $1.25 - $3.00 | $1,700 - $2,500 |
Prices include material and professional labor. DIY material-only cost is roughly $0.50-$1.00/sq ft plus blower rental.
Depth Needed by R-Value
| Target R-Value | Cellulose Depth | Fiberglass Depth | Climate Zone |
|---|---|---|---|
| R-30 | 8.6" | 12.0" | Zones 1-3 (warm) |
| R-38 | 10.9" | 15.2" | Zones 4-5 (moderate) |
| R-49 | 14.0" | 19.6" | Zones 6-7 (cold) |
| R-60 | 17.1" | 24.0" | Zone 8 / Energy Star |
Based on settled density. Source: DOE / IECC 2021 residential code. Actual depth may vary by manufacturer.
When to Choose Blown-In Over Batts
- Attic top-ups - Adding insulation over existing batts or loose-fill is the single biggest energy ROI for most homes. Blown-in covers the old insulation evenly without gaps.
- Irregular framing - Older homes with non-standard joist spacing or wiring running through cavities benefit from blown-in because it fills around obstacles. Batts leave gaps.
- Retrofit wall cavities - Dense-pack cellulose or fiberglass can be blown into closed wall cavities through small holes, making it practical for existing homes without opening walls.
- Speed - A two-person crew can blow a 1,500 sq ft attic in 3-4 hours. Cutting and fitting batts for the same space takes a full day or more.
Common Mistakes with Blown-In Insulation
- Blocking soffit vents - This is the most common DIY mistake. Install baffles at every rafter bay before blowing insulation to keep airflow from soffit to ridge.
- Under-buying bags - Coverage charts on the bag are for open attic floors at standard density. Buy 10-15% extra for irregular spaces, around HVAC ducts, and settling.
- Ignoring air sealing - Blown-in insulation slows heat transfer but does not stop air leaks. Seal penetrations (wiring, plumbing, light fixtures, attic hatches) before blowing.
- Wrong density for walls - Wall cavities need dense-pack installation (3.5 lbs/cu ft for cellulose) to prevent settling. Standard attic density (1.5 lbs/cu ft) will settle in wall cavities within a year.
Related Tools & Articles
- Insulation Calculator - Compare all insulation types including batts and spray foam
- Spray Foam Insulation Calculator - Estimate open-cell and closed-cell spray foam costs
- Attic Ventilation Calculator - Calculate NFA requirements for proper attic airflow
- How to Estimate Insulation for Your Attic - Step-by-step attic insulation guide
How to Use This Calculator
Enter the area to insulate
Measure the total square footage of your attic floor, wall cavities, or crawlspace. For attics, measure the floor area between the joists.
Select application and material
Choose where the insulation goes (attic, walls, or floor) and pick cellulose or fiberglass. Cellulose has a higher R-value per inch (3.5 vs 2.5) but fiberglass is lighter.
Set your target and existing R-value
Pick the R-value you need based on your climate zone. If topping up existing insulation, enter the current R-value so the calculator subtracts what you already have.
Review bags, depth, and cost
See exactly how many bags to buy, the depth of insulation needed, and a full material plus labor cost estimate for your project.
Blown-In Insulation Formulas
R-Value Needed = Target R - Existing R
Depth (inches) = R-Value Needed / R-per-Inch
Bags = (Area x Depth in Feet x Density) / Bag Weight
Total Cost = (Area x Depth x Material Rate) + (Area x Labor Rate)Where:
- R-per-Inch
- = Cellulose: 3.5, Fiberglass: 2.5
- Density
- = Cellulose: 1.5 lbs/cu ft, Fiberglass: 1.0 lbs/cu ft (attic settled density)
- Bag Weight
- = Cellulose: 25 lbs, Fiberglass: 30 lbs (standard bag)
Free to Embed on Your Website
Add this calculator to your blog, resource page, or client portal — just copy one line of code. Your visitors get a useful tool, you get more engagement.
EstimationPro AI For Contractors, By Contractors From Calculations to Client-Ready Estimates
You have the technical specs. Now build a professional estimate that wins the job.
Frequently Asked Questions
How many bags of blown-in insulation do I need for 1,000 sq ft?
For a 1,000 sq ft attic to reach R-38, you need roughly 20-30 bags depending on the material. Cellulose (R-3.5/inch) requires about 11 inches of depth and around 19 bags at 25 lbs each. Fiberglass (R-2.5/inch) needs about 15 inches and around 22 bags at 30 lbs each. Always buy 10% extra to account for settling and uneven coverage.
What is the R-value per inch of blown-in insulation?
Blown-in cellulose provides R-3.5 per inch at settled density. Blown-in fiberglass provides R-2.5 per inch. This means cellulose needs less depth to hit the same R-value, but fiberglass is lighter and does not absorb moisture. Both are effective when installed at the correct density.
How much does blown-in insulation cost per square foot?
Installed blown-in insulation costs $1.00 to $3.00 per square foot for most residential projects. Cellulose typically runs $1.00-$2.50/sq ft and fiberglass runs $1.25-$3.00/sq ft, installed. A 1,000 sq ft attic job averaging $1.75/sq ft comes to about $1,750 total. DIY material-only cost is roughly $0.50-$1.00/sq ft plus blower rental ($50-$100/day).
Is cellulose or fiberglass better for blown-in insulation?
Cellulose has a higher R-value per inch (3.5 vs 2.5), is made from recycled paper, and fills irregular spaces well. It costs slightly less per square foot. Fiberglass does not absorb moisture, will not settle as much over time, and is lighter. For attics, cellulose is the more popular choice. For wall cavities (dense pack), either works well when installed at the right density.
Can I blow insulation on top of existing insulation?
Yes. Topping up existing insulation is one of the most cost-effective energy upgrades you can make. Just enter your existing R-value in the calculator and it will figure out how much additional depth you need. If your existing insulation is in poor condition (compressed, water-damaged, or moldy), remove it first. Otherwise, blow right over the top.
How deep should blown-in attic insulation be?
The DOE recommends R-38 to R-60 for attics in most U.S. climate zones. In cellulose, R-38 needs about 10.9 inches and R-60 needs about 17.1 inches. In fiberglass, R-38 needs about 15.2 inches and R-60 needs about 24 inches. Check your local energy code for the minimum requirement in your area.
Do I need a blower machine for blown-in insulation?
Yes. Blown-in insulation requires a blower machine to break up the material and push it through a hose. Most home improvement stores rent blowers for $50-$100 per day, often free with a minimum bag purchase (typically 10-20 bags). For attics, a single person can operate the hose while a second person feeds bags into the hopper. Wall dense-pack requires a more powerful machine.
Why Contractors Choose EstimationPro AI
Estimates in 60 Seconds
AI generates detailed, line-item estimates from basic project details. No more hours on spreadsheets.
Accurate Pricing Data
Built on real contractor pricing and industry cost databases, updated for 2026 market conditions.
Professional Proposals
Send polished PDF estimates with your branding. Clients see a professional contractor they can trust.
Get Paid Faster
Built-in invoicing and Stripe payments. Collect deposits and progress payments directly from estimates.
Related Free Tools
Insulation Calculator
Calculate insulation needed for walls, attics, and floors. Select R-value and insulation type to get quantity, coverage, and cost estimates.
Spray Foam Calculator
Calculate spray foam insulation board feet, thickness, and installed cost. Compare open-cell vs. closed-cell foam for walls, attics, crawlspaces, and rim joists.
Stair Calculator
Calculate stair dimensions including rise, run, number of steps, and stringer length. Enter total rise and run for code-compliant stair design.
Roof Pitch
Calculate roof pitch in degrees, ratio, and percentage. Enter rise and run measurements to determine your roof slope and rafter length.
Board Foot
Calculate board feet for lumber orders. Enter thickness, width, and length to convert to board feet and estimate costs for any lumber project.
Rebar Spacing
Calculate rebar bar count, total length, and stock bars needed for a concrete slab or footing. Enter length, width, and spacing to get a complete rebar grid takeoff.
Anchor Bolt Spacing
Calculate the number of anchor bolts needed for sill plates and foundation walls per IRC/IBC code. Get bolt counts, spacing, and material cost estimates.
HVAC Load
Estimate HVAC heating and cooling load for residential spaces. Enter home size, insulation, windows, and climate zone for BTU requirements.