Insulation Calculator
Measure several wall, ceiling or floor surfaces, deduct openings and convert net coverage into whole packs. This tool estimates quantity independently of a thermal target.
Plan · Measure · Order
Insulation Calculators & Planning Guides
Plan insulation by thermal boundary and actual product coverage. Quantity, additional thermal resistance and whole-assembly performance are different questions with different inputs.
Choose a workflow
- Identify walls, attic floor, roofline, floor or foundation boundary, then measure surfaces and deduct openings. Resolve air and moisture control with the project assembly.
- For a retrofit, establish existing resistance or depth and a verified project target. For loose fill, use a complete manufacturer chart row.
- Order labeled packs, chart-based bags, sheets per layer or rated foam kits, then check the source scope and installation instructions.
Start with the project takeoff
Use the specialized tools below when the material system, thermal calculation or layout geometry requires a different method.
Coverage and retrofit
Attic Insulation Calculator
Estimate a retrofit thermal deficit from known existing R or measured depth and an entered product R per inch. Choose quantity coverage for the additional thickness.
Loft Insulation Calculator
Calculate a metric top-up from existing depth, target depth and the thickness and coverage of new rolls. First-layer and cross-layer surfaces can be recorded separately.
Blown-In Insulation Calculator
Use both constraints from a manufacturer chart: maximum coverage per bag and minimum bags per 1,000 square feet. Keep installed and settled thickness distinct.
Products and assemblies
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.
Batt Insulation Calculator
Order batts by labeled pack coverage or by the number of pieces needed for individual cavities. Piece mode prevents area-only counts from overlooking short offcuts.
Wall Insulation Calculator
Subtract windows and doors from separate wall runs, estimate full-height cavity counts and order coverage packs. Keep quantity separate from whole-wall performance.
Rigid Foam Insulation Calculator
Order sheets independently for each layer. Choose a layer count or calculate whole layers from a thermal target and the declared R of one sheet.
Insulation R-Value Calculator
Convert US R, SI RSI or an entered U-value, sum layers, or compare frame and cavity heat-flow paths. U-values are reported with their unit system explicitly identified.
Crawl-Space Insulation Calculator
Compare insulating the floor above a crawl space with insulating its perimeter walls. Add a separate rim-joist area and deduct measured openings.
Cost and quote planning
Compare dated quotes with product, location, currency and inclusions identified. Material-only and installed totals use different scopes.
Measurement, selection and installation context
These guides explain which inputs to collect and which decisions require the actual product or project specification.
Best Insulation for an Attic: Match the Retrofit Workflow
The suitable attic material depends on the thermal boundary, access and existing condition. Compare products after deciding whether the project insulates the attic floor or the roof assembly.
Best Insulation for Walls: Cavity Fit and Continuous Layers
Wall insulation is an assembly choice. Evaluate cavity dimensions, thermal bridging, existing layers and moisture control before comparing nominal material R-values.
Best Insulation for a Basement: Start with Moisture and the Boundary
Select basement insulation after identifying moisture conditions, wall construction and the intended thermal boundary. Floor area alone does not describe a foundation-wall retrofit.
Crawl-Space Insulation: Floor Above or Foundation Walls
Floor insulation and perimeter-wall insulation define different thermal boundaries. Choose a project strategy before estimating either quantity.
Mineral Wool vs Fiberglass: Fit, Declared R and Package Coverage
Compare the actual batt products at the thickness your assembly can accommodate. Material names do not establish one universal R-value, dimension or package yield.
Open-Cell vs Closed-Cell Spray Foam: Use Product and Assembly Data
Open-cell and closed-cell describe foam categories. Select an actual product and assembly before comparing thickness, yield, moisture behavior or installation cost.
Fiberglass vs Cellulose Insulation: Compare the Chart Rows
For loose-fill fiberglass and cellulose, the purchasing basis is a product-specific coverage chart. Thickness alone does not establish required bags or installed density.
Spray Foam vs Fiberglass Insulation: Compare Complete Assemblies
Compare foam and fiberglass at the same intended thermal boundary. Quantity units, air-control details and installation requirements differ, so nominal R or area price alone is insufficient.
Blown-In Insulation vs Batts: Coverage, Access and Layer Planning
Loose fill and batts use different takeoff methods. Choose a suitable assembly, then compare manufacturer-chart bags with the actual batt dimensions and layer arrangement.
Insulation R-Value by US Climate Zone: Retrofit References
ENERGY STAR publishes attic retrofit references with separate columns for bare attics and attics with 3–4 inches of existing insulation. Preserve that distinction when selecting a planning target.
Insulation R-Value per Inch: Use the Product and Application
R per inch is a product property or a clearly labeled estimate. It is not a universal constant for fiberglass, cellulose, mineral wool or spray foam.
Attic Insulation Depth: Existing, Added, Installed and Settled
Depth is useful only when tied to a material and application. Keep measured existing depth, estimated added depth, minimum installed depth and settled depth separate.
Insulation for 2×4 vs 2×6 Walls: Fit and Whole-Wall R
Nominal framing size does not supply a universal insulation R-value. Measure clear cavity depth and select a compatible product before comparing framed-wall performance.
Loft Insulation Thickness in the UK: Top-Up and U-Value Context
A loft top-up needs measured existing depth, new roll thickness and a chosen assembly target. A depth recommendation alone does not demonstrate Building Regulations compliance.
Insulation R-Values in Canada: R, RSI and Regional Verification
Canadian insulation planning should distinguish US R from SI RSI and identify the applicable provincial or territorial project requirements. NRCan retrofit advice is context, not a universal code table.
Ceiling Insulation R-Values in Australia: Assembly and NCC Context
Australian ceiling insulation depends on climate, building classification and the complete roof/ceiling assembly. A product’s bulk insulation R-value is not automatically the required Total R-Value.