1 Your project

Type feet and inches the way you'd write them, like 12' 6" or 30 3/8. Decimals work too.

ft
For walls, the total length of the walls you are insulating.
ft
Wall height for walls; width for floors and attics.
sq ft
Printed on the bag. Leave blank to use Owens Corning's kraft-faced figure.
%
For cutting around outlets, pipes and short bays.
Not sure? Look up your climate zone first.

2 What to buy

Bags to buy
3
R-13 batts, 125.94 sq ft per bag
Area to insulate
320 sq ft
we count 94% of it: a 15" batt fills 15/16 of a 16" bay
Insulation needed
315 sq ft
including waste for cuts

This uses Owens Corning's kraft-faced bag. Unfaced bags and other brands often hold fewer batts (R-13 15" × 93": 13 kraft-faced vs 11 unfaced), so enter the "sq ft per bag" from your label above.

ProductR-13 · 15" × 93" kraft (studs 16" o.c.)
Framed area320 sq ft
Cavity area (batts fill the bays, not the studs)300 sq ft
With waste315 sq ft
Coverage of the bags you buy378 sq ft

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