Insulation calculator

Starts at 0. Add a little for a wall full of openings if the offcuts will not fill the next bay.

Job sheet

Plumb insulation job sheet

40 sq ft per bag.

  • Bags25Use the coverage printed on the bag for the thickness you are installing.
Plumb insulation job sheet
40 sq ft per bag.

Bags: 25 (Use the coverage printed on the bag for the thickness you are installing.)

1,000 square feet at 40 square feet a bag is 25 bags. If the bag says 88 or 30, type that. The R-value is whatever that bag is rated for at that thickness. This page does not convert R-value into inches. The wall area can come from square feet. The board over the studs is drywall.

FAQ

How many bags?

Divide the area by the square feet on the bag. A batt package and a blown-in bag print different coverage, and the coverage changes with thickness. The 40 in the form is only a starting number. Replace it with the bag in your hand.

Blown-in or spray foam?

Same division. Blown cellulose, fiberglass, and spray foam kits all publish square feet at a given thickness. Do not reuse a batt number for foam.

Sources

  1. NIST Handbook 44: Square feet. Coverage per bag is the manufacturer’s number for the installed thickness.