How Much Insulation for a 10x12 Room?
Bags or rolls
3 bags
The four walls of a 10 by 12 room at 8 foot ceiling height, 44 linear feet of wall, framed at 16 inches on center.
When the figures look right, the insulation material list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.
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 area352 sq ft
- Stud or joist spacing16 in
- Coverage per bag or roll106.8 sq ft
Bags or rolls3 bags
| Gross area | 352 sq ft |
|---|---|
| Framing factor at 16 in oc | 90% |
| Cavity area to insulate | 317 sq ft |
| Bags at 106.8 sq ft | 3 |
| Coverage bought | 320 sq ft |
The material list this produces
| Insulation batts, bags | 3 |
|---|---|
| Vapor retarder, sq ft (if required) | 352 |
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 | 8 bags | 320 sq ft |
| 50 sq ft | 7 bags | 350 sq ft |
| 75 sq ft | 5 bags | 375 sq ft |
| 90 sq ft | 4 bags | 360 sq ft |
| 106.8 sq ft | 3 bags | 320 sq ft |
What else matters here
Forty four feet of wall at eight feet is 352 square feet, 317 of cavity, three bags. Three bags buys 320 square feet, so the margin here is three square feet, which is no margin at all.
Wall height is the input that moves this most, and it is the one most often assumed. At nine foot plates the same room is 396 square feet gross and 356 of cavity, which is four bags. At ten feet it is 440 and 396, still four bags but with almost nothing spare.
Measure the plate height rather than assuming eight feet, particularly in a basement, a garage or anything built since about 2000, where nine foot main floors are common. Batts are sold in lengths cut for standard wall heights, so the wrong height is also the wrong product, not just the wrong count.
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 a 10x12 room?
Three bags at 8 foot walls, which is 352 square feet gross and 317 of cavity. At 9 foot walls it is four.
Does ceiling height change how much insulation I need?
Directly. Insulation follows wall area, which is perimeter times height, so going from 8 to 9 foot walls adds about 12 percent.
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.