Insulation Calculator
Calculate insulation batts or rolls needed for walls and attics.
Insulation Calculator
What This Calculator Does
The Insulation Calculator tells you how many bags or rolls of insulation you need based on wall or attic area and the target R-value. Enter the surface area and select the R-value to get the number of insulation packages required, plus the coverage per package.
Proper insulation is the single most cost-effective energy efficiency upgrade for US homes. The Department of Energy recommends attic insulation of R-38 to R-60 (depending on climate zone), wall insulation of R-13 to R-21, and floor insulation of R-11 to R-19.
Federal tax credits (up to $1,200/year under the Inflation Reduction Act) are available for qualifying insulation upgrades through 2032 - check ENERGY STAR for current requirements.
How to Use
- Measure the total wall or attic floor area in square feet to be insulated.
- Select the R-value that matches your wall cavity depth and climate zone.
- Enter the area and select R-value in the calculator above.
- Click "Calculate" to see the number of bags/rolls needed.
- Check ENERGY STAR for federal tax credit eligibility on your insulation upgrade.
Reference Table
| R-Value | Wall Type | Thickness | Coverage per Bag | Common Use |
|---|---|---|---|---|
| R-13 | 2x4 wall | 3.5 in | ~40 sq ft | Exterior walls, South |
| R-15 | 2x4 wall | 3.5 in | ~35 sq ft | Exterior walls, mixed |
| R-19 | 2x6 wall | 5.5 in | ~32 sq ft | Exterior walls, North |
| R-21 | 2x6 wall | 5.5 in | ~28 sq ft | Exterior walls, cold |
| R-30 | Attic floor | 8.5 in | ~22 sq ft | Attic, South |
| R-38 | Attic floor | 11 in | ~16 sq ft | Attic, mixed |
| R-49 | Attic floor | 14.5 in | ~12 sq ft | Attic, cold |
Related Calculators
Frequently Asked Questions
🧱 Material Calculators
Explore all 25 material calculators