Blown-In Insulation Calculator: attic bags from the label chart
Blown-in insulation calculator: enter attic area, coverage per bag from the product label at your target R-value, and a waste allowance to get bags needed. A material takeoff, not a price.
How this is calculated
Every bag of blown-in insulation carries a coverage chart on the label: at a given target R-value, the bag covers a stated number of square feet (or the label states the minimum bags per 1,000 sq ft). You enter that number, the tool divides your attic area by it, and adds your waste buffer.
sq ft per bag mode:
bags_raw = area_sqft / sqft_per_bag
bags_to_buy = ceil(bags_raw × (1 + buffer))
bags per 1,000 sq ft mode:
bags_raw = (area_sqft / 1000) × bags_per_1000
bags_to_buy = ceil(bags_raw × (1 + buffer))Where the coverage number comes from: the bag. Not a table on this page, not a default, not a published average. Every insulation product (cellulose, fiberglass, mineral wool) has its own coverage chart, and the number changes with the target R-value. Read the chart at the R-value you are installing, type that number here, and the tool does the multiplication.
The optional settled-depth readout shows the depth only when you enter it. It is not used in the bag count because the bag label's coverage chart already accounts for the depth at the chosen R-value.
This calculator counts bags. It does not price the job. The attic cleanup and insulation removal pricing calculator prices the full restoration (removal, decontamination, reinsulation and haul), and if you enter a bag coverage there it also counts bags, but without the waste buffer and without this page's standalone takeoff detail. If the attic cleanup follows a rodent job, the rodent account pricing starts at the rodent control pricing calculator. The measured area for either page comes from the treatment area square footage calculator when you need to add up rectangles. And for wildlife jobs whose attic follows a different animal, the wildlife removal pricing calculator prices the removal itself.
You measured the attic, the old insulation is out, and now the question is how many bags of blown cellulose or fiberglass you need to bring to the job. Every bag carries a coverage chart on the label: at a given target R-value, one bag covers a stated number of square feet (or the label states the minimum bags per 1,000 sq ft). The arithmetic is a division, but missing it by a few bags means a second trip or leftover inventory. This calculator does the division for you, adds the waste buffer for irregular edges and obstructions, and rounds up to whole bags.
This is a material takeoff. It prints no price. If you need to price the full restoration (removal, decontamination, reinsulation and haul) or get a quick bag count inside a pricing quote, the attic cleanup and insulation removal pricing calculator builds that quote from production hours, debris volume and haul loads. If the attic cleanup follows a rodent exclusion, the rodent account begins at the rodent control pricing calculator. The measured area for either page comes from the treatment area square footage calculator when you need to add up rectangles. For wildlife jobs whose attic follows a raccoon, squirrel or bat, the wildlife removal pricing calculator prices the removal itself.
Every input is yours: the area you measured, the coverage from the bag you bought, and the waste buffer for the attic you walked. No default coverage, no default R-value, no product database. Everything runs in your browser: no account, no email gate, nothing stored or sent. Planning aid; the bag label governs.