Construction & DIY
Insulation R-Value Calculator
Add up R-values across insulation layers and estimate how much material you need.
Layers
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Total R-Value
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Vs. Target
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Additional R-Value Needed
About this calculator
R-value measures resistance to heat flow, higher is better insulated. When you stack layers (batt insulation plus rigid foam, for example) their R-values add together, so this calculator simply sums the layers you enter and compares the total to your target.
Typical recommended R-values by climate
The U.S. Department of Energy generally recommends attic insulation between R-30 and R-60 depending on climate zone, R-13 to R-21 for walls, and R-25 to R-30 for floors over unheated spaces. Colder climates need higher R-values; check your local building code for exact requirements.
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