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Insulation R-Value Calculator

Find the total R-value of an insulation layer from its thickness and material.

Inputs

Saved Scenarios

— select 2+ to compare

Total R-Value

11.2

Spark says

How it's calculated

Formula

R=Thickness×R-value per inchR = Thickness \times R\text{-value per inch}
R\text{-value per inch}
— Depends on the insulation material

What is the Insulation R-Value Calculator?

R-value measures resistance to heat flow — thicker insulation and denser/higher-performance materials both increase total R-value, which is simply thickness multiplied by the material's per-inch rating.

How to use it

  1. 1 Enter the insulation thickness.
  2. 2 Choose the insulation material.

Worked examples

3.5" fiberglass batt

About R-11.2.

Try it

Limitations

  • •Per-inch R-values are typical published figures and vary somewhat by manufacturer and installation quality (gaps and compression reduce real-world performance).

Frequently asked questions

What R-value do I need for my climate?

Building codes specify minimum R-values by climate zone and building component (walls, attic, floor) — check your local energy code rather than a single national number.