Insulation calculator

Divide the net insulated area plus your allowance by the package coverage, then round up to whole packages.

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Net area to insulate (square feet)

Package coverage at required thickness (square feet)

More inputs and assumptions

Extra material allowance (%)

Price per package

Answer

…

Divide the net insulated area plus your allowance by the package coverage, then round up to whole packages.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Enter coverage from the exact product label at the chosen thickness or R-value. Subtract openings before entering net area. The example allowance and price are hypothetical inputs. This is a material takeoff, not an R-value recommendation, code check, air-sealing design or vapor-control assessment.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-29

Using Insulation calculator

Divide the net insulated area plus your allowance by the package coverage, then round up to whole packages.

Next: Area calculator

Next: Length converter

A worked example

For net area to insulate (square feet) = 1000, package coverage at required thickness (square feet) = 40, extra material allowance (%) = 10, price per package = 30, packages to buy = 28.

Before you use the result

Example results for net area to insulate (square feet)

These examples use Package coverage at required thickness (square feet): 40; Extra material allowance (%): 10; Price per package: 30. They are reference calculations, not recommended settings.

Net area to insulate (square feet)	Packages to buy
500	14
1000	28
2000	55

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ToolOctopus. “Insulation calculator.” Updated 2026-09-29. https://tooloctopus.com/insulation-calculator.

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