Insulation Calculator
Find the insulation thickness needed for a target R-value by material, and count batt packages for an area.
Processed locally in your browser — nothing is uploaded.
Attics: R-38–R-60; walls: R-13–R-21 depending on climate
Editable — products vary
Results
- Required thickness
- 10.27 in
R-per-inch figures are typical published values; compression and gaps reduce real-world R.
About Insulation Calculator
Pick a material — fiberglass batt (R-3.7/in), blown cellulose (R-3.2/in), closed-cell spray foam (R-6/in), or rigid foam (R-5/in), all editable — and the tool divides your target R-value by the R-per-inch to get the required depth. Enter the area and package coverage to count batt packages with waste.
Common uses
- Figure out how many inches of blown cellulose reach R-49 in an attic
- Count batt packages for a garage wall project
Example
Input
R-38 target with blown cellulose (R-3.2/in)
Output
11.9 in of settled depth required
Limitations
- R-per-inch figures are typical published values; compression, gaps, and settling reduce real performance
- Doesn't model thermal bridging through studs