Spray Foam Calculator

About this calculator

Spray polyurethane foam is measured in board feet — one board foot covers 1 square foot at 1 inch of thickness — so the total board feet needed is simply the area in square feet multiplied by the target thickness in inches. Open-cell and closed-cell foam kits are sold with a rated board-foot yield (commonly 200 bf for a closed-cell kit at 1 inch, roughly double for open-cell), which determines how many kits a job requires.

This calculator takes the area to be sprayed and the desired thickness, converts it to total board feet, and divides by a kit's rated yield to tell you how many kits to buy, rounding up to account for the fact that foam yield drops in cold weather or with an inexperienced sprayer. Insulation contractors and DIY homeowners use it when quoting or budgeting a rim-joist, attic, or crawlspace insulation job before ordering foam.