Attic Insulation Calculator

Insulation depth and material from current and target R-value.

Attic area

sq ft

Current R-value

Target R-value

Insulation material

Tab to move between fields

Thickness needed

10.27 in

≈ 3 credit cards

Est. material cost

$4,108.00

≈ 4 smartphones

R-value to add38

Total R-value achieved49

Insulation volume855.9 cu ft

Bags needed (blown-in)32

Est. annual energy savings$1,000.00

How to Use This Calculator

Enter Attic area, Current R-value, and Target R-value.
Set Insulation material, Fiberglass batts (R-3.14/in), and Blown fiberglass (R-2.5/in).
Adjust Blown cellulose (R-3.7/in), Spray foam open-cell (R-3.7/in) as needed.
Review Thickness needed (in) and Est. material cost ($).
Use R-value to add and Total R-value achieved to inform your decision.

How the result changes with Target R-value

Attic area: Total attic floor area to be insulated.
Current R-value: Existing insulation R-value (0 if bare). R-11 is typical for old homes.
Target R-value: Desired total R-value. DOE recommends R-49 to R-60 for most climates.
Insulation material: Type of insulation material to install.

Thickness needed: Depth of new insulation required to reach target R-value.
R-value to add: Additional R-value needed beyond existing insulation.
Total R-value achieved: Combined R-value of existing plus new insulation.
Insulation volume: Total volume of insulation material needed.
Bags needed (blown-in): Number of bags for blown-in types. Shows 0 for batts/spray foam.
Est. material cost: Approximate material cost (labor not included).
Est. annual energy savings: Estimated yearly HVAC savings based on DOE guidelines.

Identify Input Parameters
4 parameters
Attic area = 1000, Current R-value = 11, Target R-value = 49, Insulation material = 2 = 4 input(s) provided
Calculate Thickness needed
10.27 = 10.27
Calculate Est. material cost
Est. material cost = atticArea * thicknessNeeded * costPerSqftInch
4108 = $4,108
Calculate R-value to add
R-value to add
38 = 38
Calculate Total R-value achieved
Total R-value achieved = currentRValue + thicknessNeeded * rPerInch
49 = 49