CalculatorEnter your measurements below and it works the answer out.
Area divided by coverage, plus 10% waste, rounded up to whole sheets. Enter what you measured and pick how it is sold.
The arithmetic. Work out the area, divide by what one sheet covers, add 10% waste, round up. Nothing more than that — the value of the page is the coverage figures and the waste allowance, both of which are stated here rather than hidden inside the tool.
Why the waste allowance is 10%. Measure wall and ceiling area separately and add them — ceilings are usually the sheets people forget. Deduct only openings bigger than about 32 sq ft; cutting around a normal door or window wastes more board than it saves.
How it is sold. Drywall is sold by the sheet. 4 × 8 is the sheet one person can carry; 4 × 12 gives fewer joints to tape and is what hangers prefer where the room and the stairwell allow it.
Measure the openings honestly. Deduct large openings — a garage door, a picture window, a stairwell — and ignore small ones. Cutting a sheet or a board around a normal door wastes more material than the opening saves, which is why trades quote gross area and let the waste allowance absorb it.
Round up to how it is sold. A calculator that tells you 6.3 sheets is not finished. Everything below is rounded up to whole units, because that is what you can actually buy.
Divide your area in square feet by the coverage of one sheet, then add 10% and round up. At 32 sq ft each, a 200 sq ft job needs 7.
10% is what this calculator adds. Measure wall and ceiling area separately and add them — ceilings are usually the sheets people forget. Deduct only openings bigger than about 32 sq ft; cutting around a normal door or window wastes more board than it saves.
For 8 ft walls that is 384 sq ft of wall plus 144 sq ft of ceiling, so 528 sq ft. In 4 × 8 sheets at 32 sq ft each with 10% waste that is 19 sheets.
4 × 12 if you can get it into the room, because it puts fewer butt joints in the wall and butt joints are the ones that show. 4 × 8 if you are working alone — a 4 × 12 half-inch sheet weighs about 82 lb.