Insulation Calculator
Estimate how much insulation you need by area and depth — plus bags and total cost. Switch between imperial and metric units.
Insulation Calculator
Estimate how much you need — and the cost.
- sq meters 9.75
Quick coverage reference
Batt and roll packages list the area they cover — often 40–90 sq ft depending on R-value and width. Packages = area × (1 + waste) ÷ coverage per package.
How it's calculated
- Add about 5% for trimming batts to length and fitting around framing, wiring, and obstructions.
Source: inchcalculator.com/insulation-calculator/ (package coverage by R-value cross-checked)
Common insulation uses
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</script>How much insulation do I need?
Batt and roll insulation is sold by the package, and each package lists the area it covers — typically 40–90 sq ft depending on the R-value and width. Start from the area you're insulating (walls, attic, or floor), add a small allowance for trimming, then divide by the coverage per package.
Use packages = area (sq ft) × (1 + waste%) ÷ coverage per package, rounded up. The coverage depends on the product: a higher R-value batt is thicker but covers the same floor area; the number to enter is the square footage printed on the bag. Measure stud or joist cavities by the wall or ceiling area they make up.
How to measure for insulation
Measure the area
Wall, attic, or floor area in square feet. For walls, use length × height of each insulated section.
Pick the R-value
Choose the R-value for the location and climate (attics need more than walls). It sets the batt thickness, not the area.
Enter package coverage
Read the square feet per package off the product (often 40–90 sq ft) and enter it.
Add a little for trimming
Keep about 5% for cutting batts to length and fitting around wiring, pipes, and outlets.
Insulation buying tips
A higher R-value batt is thicker and warmer but covers the same floor area. Match R-value to the wall, attic, or climate zone.
Batts come sized for 16 in and 24 in stud spacing. Buying the right width means less cutting and fewer gaps.
Batts suit open walls and accessible attics; blown-in loose-fill is sold by the bag and is better for irregular or hard-to-reach spaces.
Insulation calculator FAQ
How much area does a package of insulation cover?
It depends on the R-value and width — typically 40–90 sq ft per package. Always check the figure printed on the bag.
How do I calculate how much insulation I need?
Measure the wall, attic, or floor area, add about 5% for trimming, then divide by the square feet per package and round up.
What R-value do I need?
Attics commonly need R-30 to R-60 and walls around R-13 to R-21, depending on your climate zone. Check local code for the target.
Does a higher R-value cover less area?
No — a higher R-value batt is thicker, not smaller in area. The coverage per package still depends on width and packaging.
How do I measure an attic for insulation?
Use the attic floor area (length × width). The calculator gives the packages needed once you enter each package’s coverage.