Insulation Calculator
Estimate net square footage and whole packages for batts, rolls or rigid boards. Product coverage stays explicit, and the calculator does not choose an R-value for you.
How the insulation calculation works
Measure the surface you plan to insulate, subtract any openings you do not intend to cover, then add only the extra percentage appropriate to your layout and cutting plan.
net area = gross area − openings
purchase area = net area × (1 + extra %)
packages = ceiling(purchase area ÷ package coverage)
Use the exact package coverage
Insulation packages are not interchangeable units. Coverage varies by material, thickness, dimensions and packaging, so the calculator requires the square-foot coverage from the exact batt, roll or board product you plan to purchase.
R-value is a separate project decision
R-value measures resistance to heat flow, and recommended insulation levels vary with climate, building location and assembly. ENERGY STAR publishes climate-based guidance, but the appropriate requirement for a specific project should come from current code, project documents or qualified guidance rather than a hidden calculator default.
What about blown-in insulation?
This calculator is intentionally for products sold with a square-foot package coverage. Loose-fill and blown-in products use manufacturer-specific bag coverage that changes with installed depth, density and target R-value, so they should be calculated from the exact product chart rather than treated as the same purchase model.
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