Insulation Calculator for Walls
Estimate insulation packages for exterior walls.
Standard 2×4 exterior walls take R-13 to R-15 batts sized for the stud cavity; 2×6 walls take R-19 to R-21. Measure the wall area (length × height), subtract large openings, and enter your package coverage below.
Insulation Calculator
Estimate how much you need — and the cost.
- sq meters 9.75
Tip: Buy batts sized for your stud spacing (16 or 24 in) so they fit the cavities snugly with minimal cutting.
How it's calculated
Batt and roll packages list the area they cover — often 40–90 sq ft depending on R-value and width. Packages = area × (1 + waste) ÷ coverage per package.
See the full Insulation Calculator for the complete how-to, unit conversions, and data sources.
Insulation Calculator for Walls FAQ
What R-value for exterior walls?
R-13 to R-15 for 2×4 walls and R-19 to R-21 for 2×6 walls, depending on climate and code.
How much wall insulation do I need?
Use the wall area minus large openings, divided by the coverage per package. Match the batt width to your stud spacing.