Insulation Calculator
The Insulation Calculator estimates how many packages of batt or roll insulation you need to cover an area, based on the coverage listed on your specific product. Works in square feet or square meters. Coverage-per-package figures printed on insulation packaging assume you install the batt or roll at its full manufacturer-specified thickness; compressing it into a shallower cavity than it's rated for reduces its effective R-value, since insulation performance depends on the trapped air volume, not just the material itself. If you're insulating multiple areas with different coverage rates — say, an attic floor and knee walls — run the calculator separately for each area rather than combining the square footage into a single total, since mixing rates would give you an inaccurate package count for either area.
Switch between U.S. Customary and Metric units.
How This Tool Works
Pick your units, then enter the area you're insulating and how much area a single package of your chosen insulation covers, to get the number of packages needed.
Formula & Method
Packages needed = (area × (1 + waste%)) ÷ coverage per package (as listed on your specific insulation product). Enter area in feet with coverage in sq ft, or in meters with coverage in m².
Example Calculation
For a 500 sq ft attic using batt insulation that covers 40 sq ft per package, with the default 5% waste allowance: area with waste = 500 × 1.05 = 525 sq ft. Packages needed = 525 ÷ 40 = 13.125, rounded up to 14 packages.
Frequently Asked Questions
How do I find my insulation's coverage rate?+
Check the packaging — it's usually printed as square feet (or square meters) covered per bag or roll, and varies based on R-value and thickness.
Can I calculate insulation in square meters?+
Yes — switch the unit toggle to Metric and enter your area in meters with the package coverage in square meters.
What R-value do I need?+
Recommended R-values vary by climate zone and location in the home (attic, walls, floor) — check the U.S. Department of Energy's recommendations for your area.
Should I insulate over existing insulation?+
In many cases, yes — adding a layer perpendicular to old insulation can boost R-value, but check for moisture issues first.
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<a href="https://everyfix.net/tools/insulation-calculator/">Insulation Calculator</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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