Drywall Calculator
Enter the total area you're covering and your sheet size to get how many drywall boards to buy, with a waste percentage for cuts and breakage.
How it works
Add up every surface you're hanging board on — all four walls plus the ceiling if you're doing it. Measure or estimate that as one total square-footage number, since drywall goes on both walls and ceilings the same way.
Pick your sheet size. A standard 4-by-8 sheet covers 32 square feet, and a 4-by-12 covers 48. Bigger sheets mean fewer seams to tape, which is why pros often reach for the 12-footers on long walls.
We pad the area with your waste percentage — cutouts for outlets, windows, and doors leave scraps you can't always reuse — then divide by the sheet's coverage and round up to whole sheets.
Frequently asked questions
How much drywall waste should I plan for?
Around 10 percent works for most rooms. Small or oddly shaped spaces with lots of windows, doors, and corners waste more, so 15 percent is safer there. Long, simple walls waste less.
Should I use 4×8 or 4×12 sheets?
Twelve-foot sheets cut down on butt joints, which are the hardest seams to finish invisibly, so they're great on long walls and ceilings. Eight-footers are lighter and far easier to carry up stairs and handle solo.
Do I subtract doors and windows?
You can, but many people skip it — the offcuts around openings are often too small to reuse, and the waste percentage tends to absorb them. If a room has a huge picture window, subtracting it from your total area is reasonable.