Estimating drywall — also called plasterboard or gypsum board — is a straightforward area job: take the total surface you're covering, divide by the area of one sheet, add a margin for waste, and round up to whole boards. sheets = total area ÷ sheet area × (1 + waste). The only judgement calls are getting the area right — count walls and ceilings, subtract the big openings — and choosing a sensible waste percentage, since every cut around a corner or window leaves an offcut you usually can't reuse.
Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: standard area-coverage estimating for sheet materials.
The drywall equations
First build the total area to cover: the room perimeter times the wall height, plus the ceiling if you're boarding it, minus doors, windows and other large openings. Divide that by the area of one sheet — 2.88 m² for a 1.2 × 2.4 m board — then multiply by the waste factor and round up. The same formula handles any sheet size; just enter the dimensions of the boards you're buying.
Worked example — boarding a room
Scenario: You have 60 m² of wall and ceiling to cover, using standard 1.2 × 2.4 m sheets, and want a 10% waste allowance.
You need 23 sheets, up from a bare 21 before waste. Bump the allowance to 15% — sensible for a room with lots of corners or openings — and it rises to 24. Twenty-three 2.88 m² sheets give about 66 m² of board for 60 m² of wall, the extra covering offcuts and trims. As always, round up and keep a spare: chasing a single board mid-job costs far more time than its price.
Frequently Asked Questions
Total area ÷ sheet area, + waste. 60 m² with 2.88 m² sheets ≈ 23 with 10% waste.
1.2 × 2.4 m = 2.88 m². US 4×8 ft ≈ 2.97 m²; 4×12 ft ≈ 4.46 m².
10–15%. Simple rooms 10%; lots of corners/openings 15%+. Round up to whole sheets.
Yes if boarding it — add ceiling area (length × width) to the wall total.
Perimeter × height (+ ceiling) − openings. That net area is what you divide by the sheet area.