Enter the area you want to insulate to get the square footage of batts or rolls to buy, adjusted for framing. Match your target R-value to the product label for the correct thickness.
You need approximately
4 batt packages
covers 336 ft² (incl. waste)
Area to cover
336 ft²
Exact amount
3.81 batt packages
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Field notes
Cut batts a hair long and friction-fit them — a batt that's compressed or gapped loses R-value fast, and a 5% trim allowance covers the fussy spots around outlets and blocking. Don't stuff a thick batt into a shallow cavity to hit a higher R; compressed insulation underperforms its label. Match the batt width to your actual stud spacing (16 vs 24 inch) before you order, not after.
Measure the area to insulate in square feet and divide by the coverage printed on the batt or roll package. Add about 5% for trimming around framing and outlets.
What R-value do I need?
ENERGY STAR — a joint U.S. EPA and Department of Energy program — recommends roughly R-13 to R-21 for walls and R-30 to R-60 for attics depending on your climate zone; check the ENERGY STAR R-value map for your area.