Insulation Calculator

Add your waste percentage to the area you are insulating, then divide by the coverage printed on each roll, batt bundle, or blown-in bag at your target R-value to get the number of packages to buy, rounded up to whole packages.

Insulation Calculator

Method and assumptions

Figur turns your measurements into purchase quantities with standard geometry: it computes the area, length, or volume, applies the waste or spacing you enter, and rounds up to whole purchase units. Everything is calculated locally in your browser.

Purchase quantities round up to whole units (sheets, bundles, boards, bars, or packages) because suppliers do not sell fractions.
Assumed coverages and package sizes (for example, 3 bundles per square or 4×8 sheets) are common conventions; verify your product label and supplier.
The waste percentage is applied exactly as entered; complex cuts, patterns, and damage can require more.
The result does not replace your field measurements, plans, or local code requirements.

This tool provides a planning takeoff, not a binding bid, structural design, or engineering advice. Confirm quantities with field measurements, your supplier, and the applicable professionals before buying.

Sources and references

No external data source is required: this calculator applies standard geometry to the measurements, coverages, and waste you enter.

Frequently asked questions

Where do I find coverage per package?

Every insulation label lists the square feet one package covers at a given R-value or depth. Use the coverage for the exact R-value you plan to install, because coverage drops as R-value rises.

What R-value do I need?

Target R-values depend on your climate zone and the assembly — attics usually need far more than walls. Check your local energy code; this calculator only carries the target you enter through to the shopping list.