Insulation Calculator
Enter the area to insulate and the coverage per bag or roll to estimate how many packages you need.
Results
- Packages needed
- 14
- Area
- 500 sq ft
- Area incl. waste
- 550 sq ft
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Enter the area to insulate and the coverage per bag or roll to estimate how many packages you need.
How to use the insulation calculator
- Enter the area to insulate in sq ft.
- Enter the coverage per package in sq ft.
- Enter the waste factor in %.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Area to insulate
- 500 sq ft
- Coverage per package
- 40 sq ft
- Waste factor
- 10 %
Results
- Packages needed
- 14
- Area
- 500 sq ft
- Area incl. waste
- 550 sq ft
Using the example values above, the insulation calculator returns 14 (packages needed). Change any field to match your own project and the numbers update instantly.
How much extra should I order?
Always order a little extra. A 5% waste factor suits simple, square projects; 10% is right for most jobs; bump it to 15–20% for irregular shapes, diagonal patterns, or uneven ground. Running short almost always costs more than the leftover material.
Formula
Packages = (area × (1 + waste%)) ÷ coverage per package.
Frequently asked questions
- What R-value do I need?
- Attics often need R-38 to R-60; walls typically R-13 to R-21 depending on climate.
- How much insulation waste should I add?
- Add 5–10% for trimming around studs, wiring, and outlets.
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