Insulation Calculator
Count bags or rolls of insulation for an area.
Enter the area you're insulating and the coverage printed on the insulation package to get the number of bags or rolls needed, including a waste allowance for trimming around framing and obstructions.
How it works
Divide the area by the square footage each bag or roll covers, then add waste. Coverage depends on the product and the R-value you're installing — higher R-values cover less area per package — so always read the bag's coverage chart for your target R-value.
Frequently asked questions
How much insulation do I need?
Divide the area by the coverage per package (from the bag's chart for your R-value) and add waste. A 500 sq ft area at 40 sq ft per package needs about 14 packages with 10% waste.
Does R-value change how much I need?
Yes — higher R-values cover less area per bag or roll, so the same space needs more packages. Always use the coverage figure for your target R-value.
How much waste should I add for insulation?
About 10% for trimming around studs, joists, wiring, and outlets.
Is this calculator free and private?
Yes. Every CubicCabin calculator runs entirely in your browser, so the numbers you enter are never uploaded or stored. There's no sign-up, no limits, and it keeps working even if you lose connection after the page loads.