Insulation Calculator
Estimate insulation bags or batts by R-value.
Insulation is ordered by square feet of cavity space at a target R-value. Measure the wall or ceiling area, subtract openings, and divide by the listed bag, batt, or roll coverage. Typical targets are R-13 to R-15 for 2×4 walls, R-19 to R-21 for 2×6 walls, and R-38 to R-60 for attics.
Bags needed
25
round up
Thickness
10.3
inches
Target R
R-38
assembly
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How does the insulation calculator work?
Thickness = target R-value ÷ material R per inch. Bag count = area ÷ coverage per bag (bag coverage is printed on the bag at each target R).
What else do people ask about this calculator?
What R-value for an attic?
US DOE recommends R-38 to R-60 depending on climate zone. Most cold climates target R-49 or higher.
Blown-in vs batts?
Blown-in fills irregular spaces and adds R fast in attics. Batts are simpler for open stud/joist bays.
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