Drywall sheets for a room's walls and ceiling after doors and windows, with screws, joint tape and compound, for 4 × 8 ft or metric plasterboard.
548 ft² of board (50.9 m²) takes 19 sheets of 4 × 8 ft with 10% for cut-offs, about 548 screws, 203 ft of tape and 4.9 gal of compound (2 pails).
Rounded up to whole 4 × 8 ft sheets.
Rule of thumb: about one screw per ft² of board, from USG spacing (16 in on walls, 12 in on ceilings, framing 16 in on centre). Rounded up.
Rules of thumb from USG literature: 370 ft of tape and 9 gal of all-purpose compound per 1,000 ft² for three coats. Pails rounded up.
Board area is the wall area, 2 × (length + width) × height, plus the ceiling if included, minus doors and windows. Sheets to buy are that area plus waste divided by the area of one sheet, rounded up. Screws, tape and joint compound scale with board area at the rates used here: one screw, 0.37 ft of paper tape and 0.009 US gal of all-purpose compound per square foot.
The default 14 × 12 ft room with 8 ft walls, a ceiling and 36 ft² of openings has 548 ft² of board. With 10% waste that is 19 sheets of 4 × 8 ft, about 548 screws, 203 ft of tape and 4.9 gal of compound, or two 4.5 gal pails.
Metric sheets such as 1200 × 2400 mm are converted exactly, so results match in either unit. The drawing shows where sheet joints fall on each wall; it does not plan cuts, which is what the waste allowance covers.
Checked against: Python decimal: 2(14 + 12) × 8 + 168 − 36 = 548 ft²; × 1.1 ÷ 32 = 18.84 → 19; tape 0.37 × 548 (USG); compound 9 gal per 1,000 ft² (USG)
Checked against: Hand calculation: 2(4 + 3) × 2.4 = 33.6 m² ÷ 2.88 m² per sheet = 11.67 → 12
Checked against: Hand calculation: 4 walls × 64 ft² = 256 ft² = 8 sheets of 32 ft² with no remainder
Add the walls, 2 × (length + width) × height, and the ceiling, subtract doors and windows, add waste and divide by the sheet area. A 14 × 12 ft room with 8 ft walls has 416 ft² of wall and 168 ft² of ceiling; less 36 ft² of openings that is 548 ft². With 10% waste it needs 18.8 sheets of 4 × 8 ft (32 ft²), so buy 19.
19 sheets of 4 × 8 ft for walls and ceiling at 8 ft high, with 10% waste and no openings deducted. The walls are 2 × (12 + 12) × 8 = 384 ft² and the ceiling 144 ft², 528 ft² in all, or 16.5 sheets before waste. With 4 × 12 ft sheets (48 ft²) the same room needs 13.
At least ½ in gypsum board on the garage side of the wall separating the garage from the house, and 5/8 in Type X gypsum board where the garage has habitable rooms above it (2021 IRC Table R302.6). Sheet thickness does not change the sheet count here; order the thickness the code or your plans call for.
This calculator allows 370 ft of paper tape and 9 US gal of all-purpose compound per 1,000 ft² of board, which is 0.37 ft and 0.009 gal per square foot. For 548 ft² that comes to 203 ft of tape and 4.9 gal of compound, two 4.5 gal pails. Coverage differs between compound types, so compare with the figure on the pail.
Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “14 × 12 ft room, 8 ft walls and ceiling, 4 × 8 sheets” is checked against Python decimal: 2(14 + 12) × 8 + 168 − 36 = 548 ft²; × 1.1 ÷ 32 = 18.84 → 19; tape 0.37 × 548 (USG); compound 9 gal per 1,000 ft² (USG).
USG Sheetrock paper joint tape — coverage about 370 ft per 1,000 ft² of board; USG Sheetrock UltraLightweight joint compound — about two 4.5 gal pails per 1,000 ft²; USG Gypsum Construction Handbook — screw spacing 12 in on ceilings, 16 in on walls; International Code Council — 2021 IRC Table R302.6: garage separation, ½ in gypsum board on the garage side, 5/8 in Type X under habitable rooms.
3 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.
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