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Project DetailsMeasure the area of walls, attic floor, or crawlspace
Affiliate Disclosure: This calculator is free to use. Some product links are affiliate links. Product links and pricing are for the US market. R-value recommendations follow IECC/EnergyStar guidelines applicable to US climate zones.
How This Calculator Works
- R-value targets: Based on IECC (International Energy Conservation Code) and EnergyStar recommendations per climate zone and location in the building envelope.
- Material coverage: Fiberglass batts are sold in bags that cover a specific square footage at a specific R-value. Blown insulation is measured in bags that cover a specific area at a target depth. Spray foam is measured in board feet (1 sq ft at 1 inch thick).
- Existing insulation: If you already have insulation, the calculator determines how much R-value you need to add to reach the recommended level. Adding insulation on top of existing is common and effective.