Home & Basement

Insulation Calculator

Enter the length and height/width of the wall, attic, floor, or ceiling area to insulate. The calculator estimates package count from coverage.

Last updated: May 2026

Buying and sizing notes

Confirm required R-value, cavity depth, facing type, air sealing, and local code requirements before buying.

Insulation quantity planning tips

This calculator estimates how many packages of insulation you need. It does not choose the required R-value, so use it with the wall assembly calculator or local code requirements.

Measure the surface

Use wall length × height for walls, or length × width for attics, floors, and ceilings.

Use package coverage

Insulation packaging usually lists coverage in square feet. Enter the actual coverage for the product you plan to buy.

Leave cut allowance

Odd bays, blocking, rim joists, and framing interruptions can increase waste.

How to use this estimate

What this includes

Area from length and height/width
package coverage
waste or fit allowance

What it does not include

Choosing the required R-value
local energy-code compliance
vapor control
air sealing
specialty insulation details

Common mistakes

Using package coverage for the wrong product
Forgetting framing, blocking, or odd cavities
Buying insulation before confirming required R-value and cavity depth

Quick questions

How do I estimate insulation packages?

Measure the length and height or width of the area, enter the package coverage from the insulation label, and add a waste allowance for cuts and odd cavities.

Does this choose the right R-value?

No. It estimates quantity only. Use the wall assembly R-value calculator for performance planning and check local code for required insulation levels.

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