Spray Foam Insulation Calculator

Calculate the amount of spray foam insulation needed in board feet. Enter the area, cavity depth, and foam type (open-cell or closed-cell) to determine the amount of spray foam required and estimate material costs.

Enter Your Measurements

Area to Insulate(sq ft)

Spray Thickness(in)

Foam Type (1=Open Cell, 2=Closed Cell)

Results

Board Feet

1,500

board feet

Total R-Value

19.5

Estimated Material Cost

1,875

Spray Foam Kits (600 BF)

kits

Formula

Board Feet = Area × Thickness | R-Value = Thickness × R per inch

How to Use This Calculator

How to Use

1
Enter the total area to insulate in square feet.
2
Enter the desired spray thickness in inches.
3
Select the foam type: open-cell (R-3.7/inch) or closed-cell (R-6.5/inch).

Frequently Asked Questions

What is a board foot of spray foam?

A board foot is a unit measuring one square foot of coverage at one inch of thickness. So 100 square feet at 3 inches thick equals 300 board feet.

Open-cell vs closed-cell spray foam: which is better?

Closed-cell foam has a higher R-value (R-6.5/inch vs R-3.7/inch), adds structural rigidity, and is a vapor barrier. Open-cell is less expensive, better for soundproofing, and allows moisture to pass through. Closed-cell is preferred for exterior walls and below-grade applications.

How thick should spray foam be?

Closed-cell foam is typically sprayed 2 to 3 inches in walls and 3 to 5 inches in rooflines. Open-cell is sprayed to fill the full cavity, usually 3.5 to 5.5 inches in walls.

In-Depth Guides

📖

Insulation R-Value Guide: What You Need by Climate Zone

Understand insulation R-values for your climate zone. Covers DOE recommendations for attics, walls, and floors, plus R-value per inch for all common insulation types.

Related Calculators

Insulation Calculator

Blown-In Insulation Calculator

R-Value Calculator

About This Calculator

This calculator uses the formula: Board Feet = Area × Thickness | R-Value = Thickness × R per inch. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.

Built and maintained by the CalcSmart team. Last updated March 2026.

▶Embed this calculator on your website

Copy and paste this code into your page:

<iframe src="https://calcsmart.io/embed/spray-foam-insulation-calculator" width="100%" height="520" frameborder="0" style="border-radius:8px;border:1px solid #e5e7eb" title="Spray Foam Insulation Calculator"></iframe>

Free to embed. Attribution link included automatically.