Insulating a wall? Enter the wall size and the openings. You get the number of batts to buy for studs at 16 or 24 in.
Your shopping list
19Batts to buy
160 sq ftNet wall area
176 sq ftWall area with extra
Use batts as thick as your studs: 3.5 in for 2×4 and 5.5 in for 2×6. Extra of 10% is included.
How to use the Wall Insulation Calculator
- Enter the wall width and height. Add all windows and doors as one area.
- Pick the stud spacing that matches your wall.
- Choose the batt length and read how many batts to buy.
The math behind it
Net area = width x height – openings
Batt area = batt width x batt length / 144
Batts = net area x (1 + extra %) / batt area, rounded up
A worked example
What we typed in
- Wall width: 32 ft
- Wall height: 9 ft
- Windows and doors (total area): 60 sq ft
- Batt width: 23 in wide (studs 24 in apart)
- Batt length: 93 in (wall batt)
- Extra for mistakes and cuts: 10%
What we got
- Batts to buy: 17
- Net wall area: 228 sq ft
- Wall area with extra: 250.8 sq ft
Tips from the job site
- Cut batts to fit snugly around wires and boxes. Split them, do not stuff them.
- Use unfaced batts if there is already a vapor barrier.
Common questions
What size batt fits between studs?
Studs 16 in apart need a 15 in wide batt. Studs 24 in apart need a 23 in wide batt.
How thick are wall batts?
A 2×4 wall holds 3.5 in. A 2×6 wall holds 5.5 in.
See all Insulation Calculators.
Last checked: (worked example and form display).