Insulation Calculator

sq ft
Construction

Calculate the amount of insulation needed and the required R-value for walls, attic, or floors.

Formula

R-value per DOE recommendations by zone and location type
  • DOE/IECC climate zone recommendations used.
  • Actual R-value requirements vary by jurisdiction — check local code.
  • Batt insulation: buy sq ft coverage listed on package.

1200 sq ft attic, Zone 4

Inputs
  • Area to Insulate: 1200 sq ft
  • Location Type: attic
  • Climate Zone: zone4

Zone 4 attic → R-49. 1200 × (49/38) / 40 ≈ 38 bags blown-in.

Frequently asked questions

What is the most efficient attic insulation?
Blown-in fiberglass or cellulose is easiest for existing homes. Spray foam offers highest R-value per inch.