How Much Insulation for 1000 Square Feet?
Bags or rolls
9 bags
1,000 square feet of wall or ceiling, framed at 16 inches on center, with 106.8 square foot bags.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Wall or ceiling area1000 sq ft
- Stud or joist spacing16 in
- Coverage per bag or roll106.8 sq ft
Bags or rolls9 bags
| Gross area | 1,000 sq ft |
|---|---|
| Framing factor at 16 in oc | 90% |
| Cavity area to insulate | 900 sq ft |
| Bags at 106.8 sq ft | 9 |
| Coverage bought | 961 sq ft |
The material list this produces
| Insulation batts, bags | 9 |
|---|---|
| Vapor retarder, sq ft (if required) | 1,000 |
Coverage per bag compared
Bag coverage is the number that decides this, and it is printed on the bag. Here is the same area at five common coverages.
| Coverage per bag | Bags or rolls | Coverage bought |
|---|---|---|
| 40 sq ft | 23 bags | 920 sq ft |
| 50 sq ft | 18 bags | 900 sq ft |
| 75 sq ft | 12 bags | 900 sq ft |
| 90 sq ft | 10 bags | 900 sq ft |
| 106.8 sq ft | 9 bags | 961 sq ft |
What else matters here
A thousand square feet of framing holds 900 square feet of cavity, and nine bags at the default coverage buys 961 square feet. That is a comfortable order with 61 square feet of margin.
A thousand square feet is roughly the exterior wall area of a small single story house, or the ceiling of a 25 by 40 space. If you are doing both walls and ceiling, run them separately: the spacing is often different and the batt width certainly is.
The single biggest saving on a job this size is not the price per bag, it is not buying twice. Count the whole area first, including closets, knee walls and the band joist, and order it in one go.
What this calculator assumes
- Framing takes up roughly 10 percent of a wall at 16 inch on center and 7 percent at 24. Cavity area is reduced accordingly, so you do not buy insulation for the studs.
- Bag coverage varies a lot by R value and width. The default is a common R-13 kraft faced batt bag; read your own bag and change it.
Questions people ask
How many bags of insulation for 1000 square feet?
Nine bags at 106.8 square feet per bag, covering the 900 square feet of cavity left after framing.
Why is the cavity area less than the wall area?
Because studs and plates take up part of the wall and they are not insulated. Framing runs about 10 percent of a wall at 16 inch on center and about 7 percent at 24 inch, so the calculator takes that off before dividing.
How much does one bag of batts cover?
It is printed on the bag and it moves with R value and width. The default here is a common R-13 kraft faced batt bag at 106.8 square feet. Change it to whatever you are actually buying before you trust the count.
The insulation calculator takes any dimensions you like and hands back the same list.