Single-material calculator

Insulation Calculator

Path-aware insulation planning with R-value guidance, spec-level BOM lines, and schematic 2D / 3D previews.

Quick presets

Start from a typical North American scenario, then tune the job-specific inputs.

Inputs

Assembly

What You Are Insulating Each option has its own R-value guidance and materials. Older wall, attic, and floor links still work. Climate Zone Zones follow the DOE/IECC climate-zone map; check your county on that map if your state spans several zones. Target R-value guidance is for planning only; local energy code, permit documents, and professional review control final requirements. Wall Framing Depth Batt thickness must match the stud cavity: 2×4 walls fit R-13 or R-15, 2×6 walls fit R-19 or R-21.

Insulation settings

Insulation System Only systems supported by the selected assembly path are selectable here; each path defaults to its most common system. Target R-Value Use the recommendation unless project documents, energy modeling, or local code review calls for a different target.

Geometry

Assembly Length (ft) Type it the way you measured it - 16' 6" or 16.5 both work. Wall Height (ft)

Openings

Door Count (doors) Door Width (ft) Door Height (ft) A common residential door baseline is about 6 ft 8 in. Window Count (windows) Window Width (ft) Window Height (ft)

Advanced settings

Waste Factor (%) Package counts round up to whole packs or bags after this allowance is applied.

Regional settings

State / Pricing Region Selecting a state adjusts material prices by a state-level cost index, not by store listings in your city. States without an index keep the national baseline, and the estimate says so.

Plan insulation quantities once you know which walls, attic, ceiling, or floor you are insulating.

Reset inputs

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2D plan

Schematic quantity basis

2D and 3D previews are schematic. Drag to orbit, and scroll or pinch to zoom when 3D is open.

3D assembly

Optional 3D check

3D is optional here. Use it to sanity-check the base profile after the 2D quantity path is clear.

Insulation area Exterior wall

Location Wall

Climate zone Zone 5

Wall framing 2×6 wall (5.5 in cavity)

Insulation type Batts

Target R-value R-21

Recommended R-value R-21

Net coverage 128 sq ft

Packages 2 bags

Plan details & review

Planning assumptions

Included scope: Exterior wall.

Planning assumptions · 6

Opening deductions use simple rectangular door and window areas and do not add back odd framing pockets, rim areas, or irregular cutups.
Insulation counts are planning allowances for materials only. Air sealing, vapor control, netting, drywall, sheathing, and code-compliance detailing remain outside this scope.
Batt insulation assumes standard cavity fit and does not add separate allowances for compression, split bays, or spray-foam touch-up at irregular edges.
Exterior wall batt counts are cavity-package planning defaults only; DOE/ENERGY STAR total wall guidance may require continuous insulation or other assembly detailing.
Dense-pack blown-in wall insulation is not part of this calculator yet; wall paths cover batt and roll cavity fills only.
The BOM rounds packaged materials to whole purchase units such as gallons, bags, boxes, buckets, rolls, cartons, tubes, jars, bundles, or kits, so bought quantity can exceed the exact theoretical coverage shown by the area metrics.

Not included / Trade review

2 total scope notes to read before ordering or contractor handoff.

How pricing works

Schematic exterior wall: 20 ft x 8 ft, batts at R-21, 2 packages, climate zone 5.

Material estimate for the quantities in this plan.

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Material list

Your build list

Each line shows a purchase quantity, a coverage amount, or a planning allowance - the line says which. Check pack sizes and your site conditions before you order.

Material	Assembly	Unit	Qty	Unit price	Total	Source
R-21 exterior wall batts Calculator default	exterior wall insulation	bag	2	$125.10	$250.20	Home Depot Shopping-ready Price source: Retailer pricePrice as of: 08/09/2026Retailer: Home Depot
Quantity basis The visible row quantity is a purchase or ordering quantity. Qty: 2 Quantity type: Purchase quantity Purchase quantity: 2 Coverage: Wall cavity area minus openings, with insulation waste Waste factor: 5%

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Estimated materials total$250.20

Material guide

Insulation Basics

Switch between tabs to see how this calculator works and what stays outside its scope.

Common insulation terms used in this estimate

Quick reference only. Your local energy code and permit documents control final requirements.

R-value: How well insulation resists heat flow. Higher R means more insulating power. Energy codes set minimum R-values by climate zone and by assembly (wall, attic, floor).
Climate zone: The DOE/IECC map divides North America into zones 1 (hottest) to 8 (coldest). The zone for your county drives the recommended R-values shown here.
Batt vs roll vs blown-in: Batts are precut panels sized for stud and joist bays, rolls are continuous blankets cut to length on site, and blown-in is loose fill blown into attics with a machine.
Faced vs unfaced: Faced products bond a kraft-paper vapor retarder to one side. Which side the facing goes on depends on climate and assembly - confirm with local guidance.

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Current takeoff: 2 bags of R-21 exterior wall batts for 128 sq ft of exterior wall insulation. Plan insulation quantities once you know which walls, attic, ceiling, or floor you are insulating.

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