The short answer
Enter the area to be sprayed, the foam type and the thickness. The calculator multiplies area by thickness to get board feet, then applies Angi's and HomeAdvisor's national installed ranges of $0.60 to $1.60 per board foot for open-cell or $1.30 to $3.10 for closed-cell, plus any minimum charge and extra costs you enter. You can replace every rate with numbers from a real quote. The result is a planning range, not a quote.
Estimate your spray foam job
- Estimated installed cost
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- Board feet
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- Approximate R-value
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- Cost per sq ft sprayed
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- Minimum applied?
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A planning range, not a quote. Total = the larger of (board feet × rate) and the minimum charge, plus other costs. It does not decide whether a thickness meets code or whether a foam suits your roof or wall. Get quotes from contractors near you.
The calculator runs in your browser; no signup or personal details are needed. It does not decide code-compliant thickness or whether a particular foam suits your roof or wall.
How This Spray Foam Cost Calculator Works
The calculator uses three inputs: treated area, finished insulation thickness and an installed price per board foot. One board foot equals a 12-inch by 12-inch surface insulated to one inch thick (SPFA glossary[1]). The formula is:
- Board feet = Area (square feet) × Foam thickness (inches).
- Foam cost = Board feet × Installed rate per board foot.
- Estimated total = the larger of foam cost and the minimum job charge, plus other costs.
If you enter 1,000 square feet at three inches thick, that equals 3,000 board feet. At an illustrative $1 per board foot, the volume-based foam price is $3,000 before separately specified work. The calculator applies your minimum job charge if it is higher than the volume-based figure.
Measure the actual surface. A home’s 2,000-square-foot floor area does not mean 2,000 square feet of wall cavities or roof decking. Sloped roofs, gables and multiple wall surfaces change the treated area. For the unit math, see our board-foot cost guide.
Pricing Assumptions
There isn’t one reliable unit rate that applies to every US project. Pricing guides use different units, material versus installed costs, and different assumptions about thickness. This tool uses editable installed board-foot rates to keep its arithmetic transparent.
| Type | Default installed rate per board foot | Typical material distinction |
|---|---|---|
| Open-cell spray foam | $0.60–$1.60[2][3] | Lower density, usually lower cost per board foot |
| Closed-cell spray foam | $1.30–$3.10[2][3] | Denser, higher R-value per inch |
These default bands are the installed per-board-foot ranges published by Angi[2] and HomeAdvisor[3] (HomeAdvisor’s page updated June 17, 2026). For context, HomeGuide[4] publishes approximately $1.50–$5[4] per treated square foot installed, with thickness and application affecting the result. The two units cannot be compared directly without a depth.
The default $1,500 minimum-charge field is an illustrative setting based on HomeGuide’s report that many companies charge minimums of $1,000–$2,000[4] or more. Enter $0 if your contractor has no minimum. Update the rates and extra charges with real local bids for a more useful result.
The default R-values per inch (R-3.7 open-cell, R-6.2 closed-cell) are illustrative values inside the typical ranges the Spray Polyurethane Foam Alliance publishes: R-3.6 to R-4.5[5] for open-cell and R-5.8 to R-6.9[5] for closed-cell (SPFA FAQs[5]). Replace them with the product data sheet’s value.
Example Spray Foam Estimates by Project Size
These examples use the default installed board-foot ranges, before minimum charges and separate project costs. They are arithmetic illustrations, not local bids.
| Surface & thickness | Board feet | Open-cell estimate | Closed-cell estimate |
|---|---|---|---|
| 500 sq ft × 2 in | 1,000 | $600–$1,600 | $1,300–$3,100 |
| 1,000 sq ft × 3 in | 3,000 | $1,800–$4,800 | $3,900–$9,300 |
| 1,500 sq ft × 3.5 in | 5,250 | $3,150–$8,400 | $6,825–$16,275 |
| 2,000 sq ft × 5.5 in | 11,000 | $6,600–$17,600 | $14,300–$34,100 |
These rows do not imply that every installation should use the displayed thickness, or that open-cell and closed-cell foam can always be substituted at the same depth. Insulation specifications depend on product performance, climate, local code and moisture management.
Choosing a Thickness
Depth should come from an R-value target: divide the target R-value by the foam’s R-value per inch. The “Where is it going?” presets do this for a few common cases using the recommendations below.
The U.S. Department of Energy publishes recommended R-values for adding insulation to existing homes by climate zone (DOE Energy Saver[6]). ENERGY STAR publishes similar retrofit recommendations based on the 2021 IECC, Table R402.1.3 (ENERGY STAR[7]).
| Climate zone | Uninsulated attic | Attic with 3–4 in existing | Uninsulated floor |
|---|---|---|---|
| 1 | R30–R49 | R19–R38 | R13 |
| 2 | R49–R60 | R38–R49 | R13 |
| 3 | R49–R60 | R38–R49 | R19 |
| 4 (except Marine) | R60 | R49 | R19 |
| 4 Marine and 5 | R60 | R49 | R30 |
| 6 | R60 | R49 | R30 |
| 7 and 8 | R60 | R49 | R38 |
For uninsulated wood-frame walls, DOE lists options such as R13 in zones 1–2 and R20 (or R13 plus R5 continuous insulation) in zone 3. For basement walls, ENERGY STAR lists R10 sheathing or R13 batts in zones 4A and 4B, and R15 sheathing or R19 batts in zones 4C and 5–8.
Two practical limits: a 2×4 cavity is 3.5 inches deep, which caps open-cell at roughly R-13 in that wall; and the DOE attic figures are for attic floors. Foam under the roof deck is a different assembly with its own rules; see roof deck spray foam and building codes.
Should You Choose Open-Cell or Closed-Cell Foam?
Open-cell is typically the less expensive choice per board foot, at about R-3.6 to R-4.5[5] per inch. Closed-cell costs more per board foot but provides about R-5.8 to R-6.9[5] per inch and lower water-vapor permeance. Actual performance is product-specific.
Don’t choose foam from the price estimate alone. Roof decks, crawl spaces, basements and metal buildings can have very different drying requirements. Read our open-cell vs closed-cell spray foam guide before specifying a product.
What the Calculator Doesn’t Include Automatically
- Old insulation removal: labor and disposal are often priced separately.
- Fire protection: approved thermal or ignition barriers may be required depending on the assembly.
- Moisture repairs: existing roof leaks or damp substrates need diagnosis before insulation.
- Access costs: restricted crawl spaces, high roofs and finished walls increase labor.
- Regional conditions: travel, minimum job sizes and labor markets vary.
- Specific code requirements: the approximate R-value output is not a compliance assessment.
Enter known extra costs in the calculator. For a fuller discussion of price drivers, see the spray foam insulation cost guide or the cost-per-square-foot guide.
How to Get a Contractor Quote That Matches Your Estimate
Ask at least two or three qualified contractors to quote the same area, product, installed thickness and preparation work. The written quote should identify the foam manufacturer and product, expected installed R-value, access and masking work, fire-protection requirements, ventilation, cleanup, exclusions and warranty. An attractive unit rate is meaningless if essential work is excluded.
Spray polyurethane foam installation involves chemical exposure. Follow the manufacturer’s re-entry guidance and the EPA’s spray foam ventilation guidance (EPA[8]); don’t assume there is a universal safe re-occupancy time.
Questions owners ask
How much does it cost to spray foam 1,000 square feet?
It depends on thickness and foam type. At three inches, 1,000 treated square feet equals 3,000 board feet. Using the calculator's default installed rate bands, that's $1,800–$4,800 for open-cell or $3,900–$9,300 for closed-cell before other charges.
How do I calculate spray foam board feet?
Multiply treated surface area in square feet by thickness in inches. For example, 800 square feet at 2 inches equals 1,600 board feet.
Does this calculator include installation?
Yes, the default rates are published installed price ranges. Confirm what a local bidder includes and add any excluded items separately.
Can I use the square footage of my house?
Not unless it truly matches the area to be sprayed. For wall and roof applications, measure the actual wall or deck area rather than the home's floor area.
Why does my contractor's quote differ from the calculator?
Minimum job fees, local labor rates, surface access, masking, old insulation removal, barriers, exact product selection and other scope items can shift prices significantly.
Does the R-value estimate meet building code?
No. The displayed value is thickness multiplied by an editable R-value per inch. Compliance depends on the product, assembly, jurisdiction, climate zone and other code provisions.
Sources
- Glossary, Spray Polyurethane Foam Alliance (SPFA). Accessed October 19, 2026. Industry trade association glossary; defines a board foot as 12 in. by 12 in. by 1 in.
- How Much Does Spray Foam Insulation Cost?, Angi. Accessed October 19, 2026. National consumer cost guide from a survey of Angi customers. No update date shown; title says "2025 Data". Its installed per-board-foot ranges match HomeAdvisor's page updated June 17, 2026.
- How Much Does Spray Foam Insulation Cost?, HomeAdvisor. Accessed October 19, 2026. National consumer cost guide, updated June 17, 2026. Installed cost per board foot; national ranges, not quotes.
- How Much Does Spray Foam Insulation Cost?, HomeGuide. Accessed October 19, 2026. National consumer cost guide dated December 1, 2025. Installed cost per square foot and minimum job fees.
- Frequently Asked Questions, Spray Polyurethane Foam Alliance (SPFA). Accessed October 19, 2026. Industry trade association. Page metadata shows modified April 27, 2026. Typical density, R-value per inch, air-barrier thickness and vapor permeance ranges.
- Insulation, U.S. Department of Energy, Energy Saver. Accessed October 19, 2026. Recommended R-values by climate zone for existing homes; refers to the 2021 IECC climate zones. No date shown.
- Recommended Home Insulation R-Values, ENERGY STAR (U.S. EPA). Accessed October 19, 2026. Retrofit recommendations based on 2021 IECC Table R402.1.3. No date shown.
- Ventilation Guidance for Spray Polyurethane Foam Application, U.S. Environmental Protection Agency (archived). Accessed October 19, 2026. Last updated November 5, 2020; archived EPA page.