Insulation Calculator
Estimate batt or roll packages, blown-in bags, and spray foam kits from measured area and the coverage or yield for the product you plan to use.
Enter a known net area or measure sections and subtract openings.
Use the coverage printed on the package or roll you will buy.
Select a current loose-fill label row or enter the applicable product data yourself.
The calculator does not choose an R-value. Use the row that belongs to the product and target already selected for your project.
Board feet equal square feet of area multiplied by cured thickness in inches.
Named kit yields are theoretical manufacturer values. Actual installed coverage varies with conditions and application technique.
Default 0%. Add extra material only when your project warrants it.
Add current material price
Optional. Use the current price for the package, bag, or kit you are actually buying.
How to Use
- Choose the insulation form - Use Batts & rolls, Blown-in, or Spray foam. Each mode uses the quantity information appropriate to that product form.
- Enter the net area - Type the total area directly or build it from measured wall, ceiling, attic, or floor sections with opening deductions.
- Use current product data - For batts and rolls, enter square feet per package. For blown-in insulation, select a current label row or enter the applicable label rate. For spray foam, use the manufacturer's theoretical board-foot yield.
- Set any extra allowance - The default is 0%. Add material only when project conditions, packaging, handling, or your product guidance justify it.
- Review the purchase quantity - The calculator rounds packages, bags, and kits up to whole purchase units and keeps the underlying coverage or yield visible.
Insulation quantity depends on both project area and the coverage or yield of the exact product. Batts and rolls are purchased by package coverage, loose-fill products publish bag rates and installed thickness tables, and spray-foam kits are commonly compared by theoretical board-foot yield. This calculator keeps those three quantity methods separate instead of forcing them through one generic R-value-per-inch formula.
Measure the Area That Will Actually Be Insulated
Use the direct-area option when you already know the net square footage. For walls, ceilings, attic floors, or other repeated sections, the measured-section option keeps the takeoff auditable by multiplying length by height or width, applying quantity, and subtracting openings.
Opening deductions are area deductions. If doors, windows, attic accesses, or other uninsulated areas have already been removed from your total, do not subtract them again.
The calculator does not decide where insulation belongs or whether a specific product is suitable for an assembly. Those are design and installation questions that depend on the building, product documentation, and applicable requirements.
From Measured Area to Whole Purchase Units
Batts and Rolls Use Package Coverage
For batt and roll insulation, use the square feet of coverage printed for the package or roll you will buy. The base package count is net area divided by package coverage, rounded up. Any extra material allowance is applied to the project area before the final whole-package rounding.
The calculator deliberately does not infer coverage from batt width, length, R-value, or a generic product family. Package contents and coverage vary, so the current package label is the cleaner purchasing input.
Blown-In Insulation Uses the Product Label Table
Loose-fill insulation labels provide installation data at listed R-values, including installed or settled thickness, maximum net coverage, and bag-rate information. Choose the row that applies to the product and target you already selected. The calculator does not choose a code-required R-value for you.
When a label provides bags per 1,000 square feet, CalcShed uses that published rate directly. This matters because coverage columns can be rounded. Reversing a rounded maximum-coverage value can occasionally produce a different whole-bag count than the manufacturer's explicit bag-rate column.
Named Greenfiber SANCTUARY and Owens Corning AttiCat presets are convenience copies of current loose-fill/open-attic product data. Verify the current product documentation before purchase. For dense-pack walls or another application, use the applicable manufacturer table rather than assuming an attic row applies.
Loose-Fill Label Rates and Spray-Foam Board Feet
Spray Foam Quantity Uses Board Feet and Kit Yield
The Spray Polyurethane Foam Alliance defines one board foot as a 12-inch by 12-inch area at one inch thick. Required board feet therefore equal insulation area in square feet multiplied by cured foam thickness in inches.
Kit count is required board feet divided by the theoretical board-foot yield for the selected kit, rounded up. Named Tiger Foam presets use the theoretical yields currently published on the product pages. In particular, the TF200FR and TF600FR pages publish 180 and 529 board feet even though the model names contain 200 and 600. CalcShed uses the published theoretical yield rather than inferring coverage from the model name. Manufacturer guidance also makes clear that real coverage can vary with temperature, chemical conditions, substrate, technique, and application conditions, so theoretical yield is not a guarantee of installed coverage.
The calculator does not prescribe foam thickness or claim that a particular thickness satisfies an energy code. Enter the thickness specified for your project and product.
Why This Calculator Does Not Use a Generic R-Value per Inch
Insulation performance and coverage are product-specific. Federal R-value labeling rules require package and loose-fill disclosures, and current rules restrict simplistic R-value-per-inch claims unless the underlying testing and disclosures support them.
For quantity planning, the more defensible workflow is to use the current package coverage, loose-fill label row, or manufacturer kit yield. If you need to determine the R-value required for an assembly, use the applicable local requirements and product documentation separately.
Insulation Source Notes
- FTC insulation labeling rules specify package disclosures for batts and blankets and installation coverage information for loose-fill products. CalcShed uses those product-label quantities rather than inventing universal coverage constants.Electronic Code of Federal Regulations, 16 CFR Part 460
- Greenfiber SANCTUARY publishes loose-fill coverage and bag-rate rows used by the optional named preset.Greenfiber SANCTUARY coverage chart
- Owens Corning's current AttiCat product page provides access to the product data sheet; the optional named preset uses the May 2026 27.5 lb bag coverage table.Owens Corning AttiCat product data, May 2026
- SPFA defines a board foot as one square foot at one inch thick. Spray-foam manufacturers describe kit board-foot values as theoretical yields and warn that actual coverage varies.Spray Polyurethane Foam Alliance glossary
- The current Tiger Foam product pages provide the theoretical board-foot yields used by the optional spray-foam kit presets: 180 board feet for TF200FR, 529 for TF600FR, and 1,350 for TF1350.Tiger Foam spray foam kits
Next Steps
Once the insulation quantity is known, these calculators can help with adjacent wall and finish material takeoffs:
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Frequently Asked Questions
How do I calculate how much insulation I need?
Measure the net area to insulate, then use the purchasing basis for the exact product. Batts and rolls use package coverage, blown-in insulation uses the applicable product-label bag rate or coverage row, and spray foam uses area times thickness to calculate board feet before dividing by the kit yield.
Does this calculator tell me what R-value I need?
No. It calculates material quantity from a product and target you already selected. Required R-values depend on the building assembly, location, applicable requirements, and project conditions.
Why does blown-in insulation use bags per 1,000 square feet?
When the manufacturer publishes that rate, it is the direct installation quantity for the selected label row. Using the explicit rate also avoids small rounding differences that can appear if a rounded maximum-coverage column is reversed to recreate bag count.
What is a board foot of spray foam?
One board foot is one square foot of area at one inch thick. A 500-square-foot surface at two inches thick therefore requires 1,000 theoretical board feet before any extra material allowance.
Are spray foam kit yields guaranteed?
No. Published kit yields are theoretical comparison values. Actual installed coverage can change with temperature, substrate, equipment, technique, and application conditions.
Should I automatically add 10% extra insulation?
Not automatically. The calculator defaults to 0%. Use an extra material allowance when the product, project geometry, handling risk, installation method, or your own planning standard justifies it.