Blown-In Insulation Calculator
Estimate whole bags from the coverage chart for the exact loose-fill product and target R-value you plan to install.
How bag count is calculated
The calculator first resolves the attic, wall or other project area. When you enter the maximum coverage per bag from the manufacturer chart, it divides area by that product-specific coverage and rounds upward to a whole bag.
bags = ceiling(area ÷ coverage per bag)
The optional R-value and installed-depth fields are references only. They do not change the math by themselves because the coverage value must already correspond to those installation conditions.
Why bag coverage cannot be universal
Loose-fill yield changes with material, installed depth, density and target thermal resistance. Two products can require different bag counts for the same attic area and R-value. For that reason, ProjectCalcWorks does not hide a generic bags-per-square-foot assumption inside the result.
Use the exact coverage table printed on the bag or current manufacturer documentation. If the chart gives several rows for different R-values, select the row that matches your project requirement before entering the square-foot coverage here.
R-value is a project requirement, not a calculator default
Recommended or required insulation levels vary by climate, building component, existing assembly and applicable code. ENERGY STAR provides climate-oriented insulation guidance, but a project-specific requirement can differ. This calculator therefore records your target R-value without choosing it for you.
Blown-in versus batts, rolls and boards
This tool is for loose-fill products whose packaging provides a coverage chart. For insulation sold as batts, rolls or rigid boards with a fixed square-foot package coverage, use the Insulation Calculator instead.
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