Insulation Calculator
Enter the area and the coverage per bag or roll to get how many bags or batts of insulation you need for walls, attics, or floors.
Area to insulate
Coverage is on the bag/roll for your target R-value (blown-in coverage drops as R-value rises).
You'll need
For batts, divide your area by the square feet per bundle. For blown-in, use the coverage chart on the bag for your R-value.
How to estimate insulation
Find the area to insulate, then divide by the coverage on the product for your target R-value. Blown-in coverage drops as R-value rises, so always read the bag's chart and enter that number.
Capture attic and wall areas from a scan
ProBuildCalc turns your iPhone's LiDAR scanner into a job-site measuring kit — walk the space and it captures the square footage, material takeoff, and a blueprint automatically. No tape measure, no graph paper.
Insulation calculator FAQ
- How much insulation do I need?
- Measure the area you're insulating in square feet, then divide by the coverage printed on the bag or bundle for your target R-value. Add about 5% for waste and trimming.
- How many square feet does a bag of blown-in insulation cover?
- It depends on the R-value — a single bag might cover 40–60 sq ft at R-30 but far less at R-49. Always use the coverage chart on the bag, then enter that number here.
- How do I calculate insulation batts?
- Divide the wall or attic area by the square feet per bundle of batts. Batts are sized to fit 16- and 24-inch stud and joist spacing.
- What R-value do I need?
- It depends on climate and where you're insulating — attics commonly target R-38 to R-60, walls R-13 to R-21. Check local code, then match the coverage on the product.