Proper insulation saves 10-30% on heating and cooling costs. This calculator figures batt rolls for walls and ceilings separately, since you may need different thicknesses. Always add waste factor for cuts and fittings.
Total Rolls Needed:
Achievable R-Value:
How to Use This Tool
Enter wall and ceiling areas in square feet.
Enter target R-value for your climate zone.
Enter the R-value and coverage of the roll you are buying.
Set waste factor (10%).
Click Calculate.
The Formula
Rolls = Area / Coverage Per Roll x (1 + Waste%). Attic code typically requires R-38 to R-60.
Why It Matters
You are insulating a 1,500 sq ft attic with R-38 fiberglass batts. Each batt covers 16 sq ft — you need 94 batts. With 10% waste: order 104. This saves an estimated $400/year on heating and cooling.