Insulation Calculator - R-Value, Batt Rolls & Blown-In Bags

Calculate insulation batts, rolls, and blown-in cellulose or fiberglass bags based on DOE climate zones, target R-values (R-13 to R-60), and attic/wall area.

⚙️ Configuration & Inputs

Total Area to Insulate (sq ft) Attic floor, exterior walls, or crawlspace

Application & R-Value Target

Framing Stud / Joist Spacing

📊 Results & Analysis

Fiberglass Batt Bags / Rolls 29 Bags (R-49) Coverage: ~42 sq ft per bag

Blown-In Cellulose Bags 71 Bags 30 lb bags (installed thickness: 13.8")

Blown-In Fiberglass Bags 84 Bags Installed depth: 18.5 inches

Annual Energy Cost Savings $280 - $420 / yr EPA Energy Star heating/cooling estimate

DOE Climate Zones & Recommended R-Values

R-value measures thermal resistance—the higher the number, the greater the insulating power.

Zone 1-3 (Southern US): Attic R-30 to R-38.
Zone 4-7 (Northern / Midwest US): Attic R-49 to R-60.
2x4 Walls: R-13 or R-15 batts.
2x6 Walls: R-19 or R-21 batts.

Frequently Asked Questions

Yes, as long as the existing insulation is dry and free of mold. Lay unfaced batts perpendicular across the ceiling joists to cover thermal bridges.

Faced insulation includes a kraft paper vapor retarder that must face toward the conditioned interior living space to prevent moisture condensation.