Insulation Calculator
How much insulation for a wall or attic? Pick the US DOE climate zone for the recommended R-value and the product type, and get bags or sheets with waste.
Wall area or attic floor area. For walls: perimeter × height.
Zones 1–2 are hot, 3–4 mixed, 5–7 cold, 8 subarctic. Colder zones need a higher R-value.
Insulation for 1,000 sq ft — climate zone 3-4
10 bags — 1,050 sq ft to cover with 5% waste
Recommended R-values for zone 3-4: walls R-13, attic R-38 (US DOE guidance). The product you picked covers about 106 sq ft per bag at its rated depth. Do not compress batts — a squashed R-19 batt performs like a much lower R-value — and air-seal gaps before insulating; insulation slows heat, it does not stop air leaks.
Estimate. Bag and sheet coverage vary by brand and by the depth installed — confirm the coverage printed on the product. R-value recommendations are US DOE guidance, not code; check your local building code.
Formula used: Units = area × (1 + waste%) ÷ coverage per bag or sheet, rounded up. Recommended R-values follow the US DOE climate-zone table.
How this estimate works: Insulation is bought by coverage: the tool adds a small waste allowance to the area and divides by the coverage of the product you picked. The climate zone sets the recommended R-value — colder zones need thicker insulation — and the product type sets how many bags or sheets that R-value takes, because coverage per bag falls as the rated depth rises.
How the insulation calculator works
Insulation is bought by coverage: the tool adds a small waste allowance to the area and divides by the coverage of the product you picked. The climate zone sets the recommended R-value under US DOE guidance — colder zones need thicker insulation — and the product type sets how many bags or sheets that R-value takes, because coverage per bag falls as the rated depth rises. Do not compress batts, and air-seal gaps before insulating: insulation slows heat, it does not stop air leaks. Check your local building code — the DOE figures are guidance, not code.
Try next: Drywall Calculator · Decking Calculator · Fence Calculator
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