Insulation R-Value Calculator
Compare your current insulation against a target R-value and see how much additional depth of your chosen material is required.
- Current R-value
- R-12.8
- Total depth after upgrade
- 15.3 in
- Material volume
- 848.4 cu ft
- · Never compress insulation to fit — compressed batts lose a large share of their rated R-value.
How to use the Insulation R-Value Calculator
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01
Measure the existing insulation depth without compressing it.
-
02
Select the closest material type and enter the target R-value for your climate zone.
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03
Measure the total area that needs insulation.
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04
Use the extra-depth result to compare products, then confirm local code and assembly requirements.
Frequently asked questions
Can different insulation layers be combined?
Yes. R-values generally add, provided layers are dry, correctly installed and not compressed.
Why does climate zone matter?
Recommended roof, wall and floor R-values vary with local heating and cooling conditions and building codes.
Does this include the rest of the assembly?
No. It estimates insulation only; framing, sheathing and air films also affect whole-assembly performance.
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These calculators give planning estimates based on the figures you enter. They are not a substitute for a site survey, a structural or load calculation, or professional advice. Always confirm quantities with your supplier or contractor before ordering.