Choose your climate zone and assembly type, add your material layers, then calculate. Formula: R (per layer) = Thickness × R-per-inch, summed across all layers + air films if included.

Climate Zone & Assembly

Your climate zone sets the IECC code-minimum R-value this calculator compares your result against.

IECC Climate Zone
Assembly Type

Material Layers

Not sure what a field means? Tap the ⓘ next to its label. Add every layer in your assembly — insulation, sheathing, drywall — for the most accurate total.

Units

R-value-per-inch figures are standard published values (ASHRAE / U.S. DOE) for each material type and can vary by manufacturer, density, and installation quality. Select Custom to enter your own known value.

Air Films, Framing & Current R-Value

All three are optional — turn on what applies to your situation.

Include Air Films
Include Structural Framing

Your Results

Total R-Value
—
°F·ft²·hr/BTU
U-Value
—
1 ÷ R
Code Minimum
—
for your zone
Compliance
—
vs. code minimum
Formula: —
Layer Contribution to Total R-Value

Each bar segment shows how much one material layer contributes to your total R-value.

Layer contribution chart.
MaterialThicknessR-Value
Total (before air films / framing)—

Results are for reference and estimation only. Actual thermal performance varies with installation quality, moisture, compression, and material variability. See full disclaimer below.

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