Construction Calculators Logo

All Calculators

Building Materials iconBuilding MaterialsConcrete iconConcreteDecks iconDecksDemolition iconDemolitionDriveways iconDrivewaysElectrical iconElectricalFencing iconFencingFinancing iconFinancingFlooring iconFlooringHVAC iconHVACInsulation iconInsulationLandscaping iconLandscapingLighting iconLightingMasonry iconMasonryPatios iconPatiosPlumbing iconPlumbingPools iconPoolsRemodeling iconRemodelingRoofing iconRoofingSiding iconSidingSite Preparation iconSite PreparationWalls & Ceilings iconWalls & CeilingsWaterproofing iconWaterproofingWindows & Doors iconWindows & Doors

Blow-in Insulation Calculator

Calculate the amount of blow-in insulation needed for your attic to achieve the desired R-value. This helps you estimate materials, costs, and weight for your insulation project.

How to Use Blow-in Insulation Calculator

The calculator determines the attic area and calculates the additional depth needed, then determines the number of bags required based on the coverage rate for your chosen insulation type and density.

Insulation Types

  • Cellulose: Most common, made from recycled paper, good fire resistance
  • Fiberglass: Lightweight, good coverage, moisture resistant
  • Mineral Wool: Fire resistant, sound absorbing, higher cost

R-Value Guidelines by Climate Zone

  • Zone 1-2 (Southern states): R-30 minimum (10 inches)
  • Zone 3-4 (Central states): R-38 minimum (12 inches)
  • Zone 5-6 (Northern states): R-49 minimum (14 inches)
  • Zone 7-8 (Extreme northern): R-60 minimum (17 inches)

Coverage Guidelines

  • Cellulose: 40 sq ft per bag (R-3.5/inch)
  • Fiberglass: 35 sq ft per bag (R-3.5/inch)
  • Mineral Wool: 30 sq ft per bag (R-3.5/inch)
  • Coverage varies with density and R-value per inch

Installation Tips

  • Buy 10-15% extra for settling and waste
  • Ensure proper attic ventilation before installing
  • Don't cover soffit vents or exhaust fans
  • Wear protective equipment (mask, goggles, gloves)
  • Check local building codes for minimum R-values
  • Consider professional installation for large areas

Cite this page as:

Daniel, P. Blow-in Insulation Calculator. Available at: https://constructioncalculators.com/blow-in-insulation-calculator/. Accessed: October 25, 2026.