Attic Insulation Calculator
Multiplies attic floor area by depth to get volume, then divides by a typical 33 cu ft blown-in bag coverage planning number.
Step 1: Units
Step 2
Enter project measurements
Use decimals if needed (e.g. 3.5).
Step 3
How to use this calculator
Measure attic floor length and width and desired settled depth.
What the math is doing
Volume = area × depth. Bags ≈ cu ft ÷ 33 per bag.
Frequently asked questions
Settled depth?
Use manufacturer settled thickness, not blower hose peak.
Baffles at eaves?
Maintain vent channel before adding depth.
Recessed lights?
Use rated covers before burying with insulation.
Air sealing first?
Yes; air leaks undermine R-value gains.