Insulation Calculator
Find the recommended R-value for your attic, walls, or floor by climate zone — and estimate how many batt packs or bags you need to cover the space.
Coverage varies by product and R-value — always check the package label before buying.
How to Calculate Insulation
Start with the area you need to insulate in square feet — for an attic or floor, that's simply length × width; for walls, it's the total wall surface. Then pick the target R-value recommended for your climate zone and the part of the home you're insulating. Colder zones (5–7) call for much higher attic R-values (up to R-60) than warm southern zones (R-30).
To find how many batt packs or bags to buy, divide the area by the coverage printed on the package, then add about 10% for trimming, gaps, and offcuts. This calculator rounds up to whole packs so you don't come up short. Coverage per pack changes with the R-value and thickness, so confirm the exact square footage on the label of the product you choose.
Frequently Asked Questions
What R-value do I need for my attic?
It depends on your climate zone. The U.S. Department of Energy recommends R-30 in the warmest zones (1) and up to R-49 to R-60 in colder zones (4–7). Select your zone above to see the exact recommendation for an attic, wall, or floor.
How much insulation do I need?
Measure the square footage of the space, then divide by the coverage per batt pack or bag (shown on the label, often around 40 ft²) and add 10% for waste. Round up to whole packs. This calculator does that automatically once you enter your area.
How do I calculate insulation coverage?
Each package of batts or loose-fill lists the square footage it covers at a given R-value. Divide your total area by that number to get the packs required. Higher R-values cover fewer square feet per bag, so check the chart on the package.
Turn Your Measurements Into a Real Floor Plan
Once you know your dimensions, generate a labeled, to-scale floor plan in seconds — then export it to DXF or build it in 3D. No CAD experience needed.
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