Insulation · Project planning

Spray Foam Insulation Calculator

Convert area and thickness into board feet, then compare planned yield with the rated kit yield. A target-R mode uses your product’s declared R per inch.

By Alish Gautam, Software Developer · Updated 4 October 2026 · Calculation methodology

Start with the editable example below. Dimensions retain their physical size when units change. Region sets currency labels without converting currencies; confirm entered quotes after changing region. Thermal inputs labeled US R retain that unit in every region.

Measured insulation surfaces

Use non-overlapping rectangles. Enter openings as area on the surface they interrupt.

Room / surface 1

Surface label

Surface length / wall run (ft)

Surface width / height (ft)

Uninsulated opening area (ft²)

Basic settings

Calculation modeChoose the estimating method.

Product settings

Product and system dimensions

Application thickness (in)Editable arithmetic example. Replace with your project or product specification.

Rated kit yield (board feet)Editable arithmetic example. Replace with your project or product specification.

Product / specification referenceOptional supplier product name, chart revision or quote reference, saved in shared project state.

Advanced settings

Advanced planning settings

Purchase allowance (%)Planning allowance, not a code or industry requirement. Set zero to order the exact rounded takeoff.

Cost settings · USD

Optional quote prices

Price per purchased pack / unitOptional supplier quote in the selected currency. Blank omits cost.

Project takeoff

Whole packages round up. Allowance is separate from purchased surplus. Prices omit labor, delivery, tax and other items unless explicitly entered.

Gross measured area: 120 ft²
Opening / exclusion deductions: 0 ft²
Application thickness: 2 in
Net requirement: 240 board feet
Allowance: 24 board feet
Planned requirement: 264 board feet
Unrounded package requirement: 0.44
Kits to buy: 1
Purchased coverage: 600 board feet
Surplus beyond planned requirement: 336 board feet

Supplier-ready material list

Kits to buy: 1

Geometry / layout breakdown

Dimensions use the selected measurement system.
Surface	Material	Gross (ft²)	Net (ft²)
Room / surface 1	floor	120	120

Rated yield is not guaranteed installed yield. Temperature, application losses and thickness limits follow the product instructions; one R per inch cannot represent every foam.

How it works

Board feet = area in ft² × thickness in inches. Kits = ceil(board feet × (1 + allowance) / rated yield).

Assumptions and limitations

Rated yield is not guaranteed installed yield. Temperature, application losses and thickness limits follow the product instructions; one R per inch cannot represent every foam.

Whole packages round upward after the chosen allowance. Physical geometry and purchase reserve are separate. Manufacturer and project specifications override editable examples; the selected region does not establish a local code requirement.

Sources and boundaries

Natural Resources Canada: Keeping the Heat In — Section 3: Materials

Open the source · Web guidance; edition not stated · Reference checked 2026-10-04

Scope: Material and thermal-control guidance

Used for: R versus RSI terminology; Assembly-specific material considerations.

Does not establish: All products share one R per inch; Provincial code lookup.

Thermal conversion is a unit conversion; product resistance is an input.