Drywall Calculator

How drywall quantities are calculated

Drywall is bought by the sheet, so everything starts from the square footage to cover:

Wall area = 2 × (length + width) × ceiling height
Ceiling area = length × width (only if included)
Sheets = total area ÷ sheet area (32 sq ft for a 4×8, 48 sq ft for a 4×12), rounded up

Screws: a common planning figure is about 1 screw per square foot of board — roughly 32 screws per 4×8 sheet at standard 16-inch stud spacing. A 1 lb box holds about 200 screws, so the result above also converts to boxes.

Joint compound: plan on roughly 1 gallon of ready-mix compound per 100 sq ft to tape seams and apply finish coats. A standard 4.5-gallon bucket therefore covers about 450 sq ft. Taping also uses about 1 roll (250 ft) of paper tape per 500 sq ft of board — worth adding to the same shopping trip.

Doors and windows? This calculator doesn't subtract them, on purpose: the offcuts around openings, plus breakage and cutting mistakes, eat up most of what you'd save. For a room with unusually large openings (a full glass wall, a big garage door), subtract that area yourself or add one fewer sheet. Ordering 1–2 extra sheets beyond the result is cheap insurance — an unopened sheet can usually be returned.

Frequently asked questions

4×8 or 4×12 sheets? 4×12 sheets mean fewer seams to tape and finish, but they're heavier, harder to maneuver, and may not fit down a hallway or stairwell. 4×8s are the DIY default; 4×12s shine in long, straight rooms with 9–12 ft ceilings hung vertically.

How thick should the drywall be? 1/2 inch is standard for walls; 5/8 inch is used for ceilings on wide joist spacing and where fire ratings are required; 1/4 inch is for going over existing surfaces or gentle curves. Thickness doesn't change the sheet count.

Does the ceiling really need drywall? Only if you're finishing it — many basements use drop ceilings or leave joists exposed, in which case uncheck the ceiling box and the count drops by the ceiling area.