You'll need about
12
bags / rolls
46
m²
4
m² per pack
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How this is calculated
bags or rolls = area ÷ coverage per package (rounded up). Coverage depends on the target R-value — a bag of blown-in insulation covers fewer square feet at a higher R-value because it is filled deeper. Use the coverage chart printed on the bag for your R-value.
This is a planning estimate — always confirm against your supplier and the specifics of the job before ordering.
Insulation calculator: FAQ
How much insulation do I need?
Divide the area you are insulating by the square feet one bag or roll covers at your target R-value, then round up. The coverage figure is on the package.
How do I calculate blown-in insulation bags?
Each bag lists the maximum coverage at a range of R-values — the higher the R-value, the fewer square feet per bag because it is installed deeper. Divide your attic area by the coverage at your target R-value.
What R-value do I need?
It depends on climate and location. Attics are commonly R-38 to R-60, walls R-13 to R-21. Check your local energy code for the requirement in your area.
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