Floors & Walls
Blown Insulation Calculator
Estimate loose-fill bag counts from the manufacturer's coverage row for your exact product and depth.
Enter your measurements
Results update as you type.
About this calculator
Loose fill is bought by the bag, and coverage per bag depends on the product and the target depth. Enter the area, the coverage per bag printed on the manufacturer's chart for your product and depth, and an allowance for fitting. The calculator will not scale between R-value rows or guess a depth for you.
How to measure
- Measure the attic or cavity area to receive loose fill. Add rectangular sections if the space is divided.
- Use the bag coverage in the exact manufacturer chart row for your selected product, depth and target R-value.
- Confirm the coverage basis before calculating; this tool does not choose an R-value or interpolate chart rows.
How to use this calculator
- Measure the area to fill.
- Find your product's chart row for the depth you will install.
- Enter that coverage per bag exactly.
- Add an allowance for uneven depth and fitting.
- Calculate for bags to buy.
Formula
Order area = area × (1 + allowance ÷ 100)
Bags = ⌈order area ÷ matching label coverage per bag⌉
No interpolation between R-value rows and no depth inferred from an R-value
Assumptions
- Loose-fill bags only — batt/roll product is a separate calculator.
- Coverage is the manufacturer's figure for the exact product and depth entered.
- Selecting a named attic reference replaces the coverage field with that archived chart value. The bag calculation uses the coverage currently shown; the custom option requires your own product chart.
Common mistakes
- Using a coverage or yield for a different product, depth or application.
- Adding waste twice in both the measured quantity and allowance field.
- Treating a bag count as proof that the selected product is suitable for the installation.
Worked example
Try it: press “Load example” above the form.
1,000 ft² at 40 ft² per bag with no allowance needs exactly 25 bags.
Limitations
No R-value design, settlement correction, thermal compliance or machine settings. Coverage must come from a matching manufacturer chart.
Frequently asked questions
Does changing R-value change bag coverage?
Selecting a named AttiCat attic reference explicitly replaces the coverage field with that chart’s value. Custom products require their own chart. Minimum thickness and bag count must both be satisfied.
Can I use the attic chart inside wall cavities?
No. Closed-cavity applications have different density and coverage requirements. The named reference is for open attics only; use the exact product and application chart.
What does the worked example show?
1,000 ft² at 40 ft² per bag with no allowance needs exactly 25 bags.
Which assumptions should I check before using the result?
No R-value design, settlement correction, thermal compliance or machine settings. Coverage must come from a matching manufacturer chart.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
- Owens Corning: product coverage charts
Coverage varies by product, target depth and region. No manufacturer yield is supplied as a preset.
- Owens Corning: archived AttiCat manufacturer fact sheet
Archived open-attic manufacturer chart for nominal 28.5 lb bags. The selected reference fills coverage only. Confirm the current exact bag label, required bag count and minimum installed thickness; this is not a current-product or closed-cavity specification.
Calculation documentation · Updated 2026-11-11 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
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