Planning with batts or rolls? Enter the area and the coverage printed on the package. You get how many rolls or bags to buy.
Your shopping list
28Rolls or bags to buy
1,000 sq ftArea after openings
1,100 sq ftArea with extra
Packages of the same R-value can cover different areas, so use the number on your package.
How to use the Batt and Roll Insulation Calculator
- Measure the area and take out the openings.
- Read the coverage on your package. It is in sq ft.
- Read how many packages to buy.
The math behind it
Net area = area – openings
Packages = net area x (1 + extra %) / coverage, rounded up
A worked example
What we typed in
- Area to insulate: 1,800 sq ft
- Windows and doors (total area): 120 sq ft
- Coverage of one roll or bag: 50 sq ft
- Extra for mistakes and cuts: 10%
What we got
- Rolls or bags to buy: 37
- Area after openings: 1,680 sq ft
- Area with extra: 1,848 sq ft
Tips from the job site
- Packages of the same R-value can have different coverage. Check each label.
- Buy one extra roll for odd cuts if the job is small.
Common questions
How much does one roll of insulation cover?
It depends on the roll. The coverage is printed on the package, so type that number in.
Should I add extra for waste?
Yes. 5 to 10% covers cuts around pipes, wires and corners.
See all Insulation Calculators.
Last checked: (worked example and form display).