Insulation Calculator – Estimate Fiberglass & Blown Insulation Quantity

Installing attic, wall or crawl space insulation requires precise material calculation. Many homeowners underestimate rolls and bags due to cut waste around joists, pipes and vents. This free insulation calculator computes total square footage and required insulation material with customizable waste factor for residential energy upgrade projects.

Insulation quantity results appear here

Tip: Attic projects with many rafter vents use 10–15% waste allowance for cutting.

Tool Features

Common Usage Scenarios

Frequently Asked Questions

Q: How much waste should I add for attic insulation?

A: Standard simple attic:8–10% waste. Attics full of plumbing and vent openings use 12–15% extra insulation.

Q: What insulation type is better for old attics?

A: Blown loose-fill insulation fills gaps better than fiberglass rolls for uneven older roof framing.