Insulation Calculator
Estimate the bags of blown-in insulation or the batts required to reach a target R-value in an attic or wall cavity.
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Estimated cost
$1,300 – $2,300
Typical figure around $1,800.
- Area
- 1,000 sq ft
- Material units
- 25 bags
- Coverage per unit
- 40 sq ft
Material only. Blown-in installation is usually included in the price when a contractor supplies the machine.
Planning estimate only — confirm quantities with your supplier or contractor before ordering.
How this estimate is calculated
The estimate is built from area to insulate (sq ft) and insulation type, then priced at national average rates. It reports area, material units and coverage per unit, with quantities rounded up so you are never short of material and the standard waste allowance already included where it applies.
Material only. Blown-in installation is usually included in the price when a contractor supplies the machine.
The dollar range is a national average, so treat it as a starting point rather than a bid. Labor rates, permit fees and material delivery differ by region — the state table below shows how your state compares, and construction cost by state breaks the picture down further.
Prefer the longer version? Read our guide to How much does a roof replacement cost and How much does it cost to replace windows and How much does it cost to replace a water heater and How much do Andersen windows cost and How much do Pella windows cost and How much do Marvin windows cost and How much does soffit replacement cost and How much does siding replacement cost and Replacement windows vs window inserts: what actually differs.
Cost by insulation type
Each row prices the same default job shown in the calculator above, changing only the insulation type. Use it to see what the upgrade or the cheaper option really costs before you commit.
| Insulation type | Low | High |
|---|---|---|
| Blown-in fiberglass (R-49) | $1,300 | $2,300 |
| Blown-in cellulose (R-49) | $1,500 | $2,600 |
| Fiberglass batts (R-13) | $800 | $1,600 |
| Spray foam (R-20) | $2,500 | $4,500 |
What the same job costs by state
Every row applies that state's construction cost index to the national range calculated above. The index bundles local labor rates, permit fees and material delivery, so it is a planning figure rather than a bid.
| State | Index | Low | High |
|---|---|---|---|
| Ohio | 0.92 | $1,196 | $2,116 |
| Texas | 0.93 | $1,209 | $2,139 |
| North Carolina | 0.94 | $1,222 | $2,162 |
| Georgia | 0.95 | $1,235 | $2,185 |
| Arizona | 1.01 | $1,313 | $2,323 |
| Florida | 1.02 | $1,326 | $2,346 |
| Pennsylvania | 1.03 | $1,339 | $2,369 |
| Illinois | 1.05 | $1,365 | $2,415 |
| Colorado | 1.08 | $1,404 | $2,484 |
| Washington | 1.15 | $1,495 | $2,645 |
| California | 1.32 | $1,716 | $3,036 |
| New York | 1.42 | $1,846 | $3,266 |
Index 1.00 is the national average. See construction cost by state for metro-level figures and the projects homeowners ask about most.
Where to buy materials
Links to suppliers are sponsored: if you buy through them, we may earn a commission at no extra cost to you. It never affects an estimate.
- Search The Home Depot“blown-in insulation bags”
- Search Lowe's“blown-in insulation bags”
Frequently asked questions
What R-value do I need in an attic?
The US Department of Energy recommends R-49 to R-60 for most attics in cold climates, and R-30 to R-49 in mild climates. Check the recommendation for your zip code before buying.
Is blown-in insulation cheaper than batts?
Blown-in fiberglass is often cheaper per square foot for attics because it fills gaps and joist bays quickly. Batts cost less per bag but leave more gaps when installed poorly.
How many bags of blown-in insulation do I need?
For a 1,000 sq ft attic at R-49, plan on about 25 bags of blown-in fiberglass at 40 square feet of coverage each, or about 29 bags of cellulose at 35 square feet each. Buying by coverage rather than by R-value is what keeps the estimate honest.
How much does attic insulation cost?
Blown-in fiberglass costs about $1.30 to $2.30 per square foot of material, so a 1,000 sq ft attic runs roughly $1,300 to $2,300. Cellulose is slightly more at $1.50 to $2.60, and spray foam is several times that.
Does this cost change from state to state?
Yes. Applying each state's construction cost index to the national range of $1,300 to $2,300, the same job runs from about $1,196 to $2,116 in Ohio (index 0.92) to $1,846 to $3,266 in New York (index 1.42).
What is not included in this estimate?
Material only. Blown-in installation is usually included in the price when a contractor supplies the machine. The figure is a national planning average for the work described above, not a contractor's quote.
