Walls & Paint Calculators

Wall materials, measured the way pros measure them

Start with paint, the most underestimated purchase in any renovation. Manufacturers rate coverage at 350–400 sq ft per gallon per coat, and the honest planning figure is 350. Then deduct about 21 sq ft per door and 15 per window, and multiply by your coats. The calculator does all three steps and converts the answer into the gallons and quarts you'd actually buy.

Masonry walls run on unit tables, not area guesses. The Brick Calculator uses the manufacturers' units-per-square-foot table (a modular brick needs 6.86 bricks per sq ft with a standard 3/8 in joint), and plans mortar at the conservative end of the makers' published range so you don't run short mid-wall. For the inside of the wall, the Drywall Calculator counts sheets and then the supplies everyone forgets: joint compound at USG's published rate of about 10 gallons per 1,000 sq ft, tape by joint geometry, and screws by the pound.

Finishing layers have their own traps. Wallpaper is sold in double rolls of 56.4 sq ft, but pattern repeat eats the yield, down to about 28 sq ft usable on a large repeat. And insulation is rated by R-value, with blown-in coverage following Owens Corning's published chart bag-for-bag. Each calculator here is built on the manufacturer's own figures for its material, not on a generic rule of thumb.