Drywall Calculator Widget
Help renovators order plasterboard for a whole room. From the room's length, width and wall height, the doors and windows and the sheet size, the widget counts the drywall sheets for walls and ceiling and estimates the screws, joint compound and paper tape.
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How it works
Wall area is the room perimeter times the wall height, less a standard door (3 x 7 ft, or 0.9 x 2.1 m) and window (3 x 5 ft, or 1.2 x 1.2 m) for each one counted; the ceiling, if included, is length x width. Walls and ceiling are sheeted separately, each grossed up by the waste allowance and divided by the sheet area, then rounded up. Screw counts follow USG's maximum fastener spacing of 16 in on walls and 12 in on ceilings: a 4 x 8 ft sheet across studs at 16 in centres touches 7 studs with 4 screws on each (28), or 5 on each on a ceiling (35). Joint compound uses USG's figure for its all-purpose ready-mixed compound - about 10 gallons per 1,000 sq ft of board - and paper tape about 370 ft per 1,000 sq ft. A 12 x 12 ft room with 8 ft walls, one door and two windows has 333 sq ft of wall and 144 of ceiling: 17 sheets, about 511 screws, 4.8 gallons of compound and 176 ft of tape.
Calculation method
- Walls = 2 x (length + width) x height - doors x 21 sq ft (1.89 m2) - windows x 15 sq ft (1.44 m2)
- Sheets = ceil(walls x (1 + waste) / sheet area) + ceil(ceiling x (1 + waste) / sheet area)
- Screws per sheet = (sheet length / framing spacing + 1) x (sheet width / screw spacing + 1); screw spacing 16 in walls, 12 in ceilings (400 / 300 mm metric)
- Joint compound = area / 1,000 sq ft x 10 US gal; tape = area / 1,000 sq ft x 370 ft
Worked examples
Bedroom with ceiling
Inputs: 12 x 12 ft; 8 ft walls; 1 door; 2 windows; 4 x 8 ft sheets; studs at 16 in; 10% waste
Result: 17 sheets; about 511 screws; 4.8 gal compound; 176 ft tape
Walls 384 - 21 - 30 = 333 sq ft -> 12 sheets; ceiling 144 -> 5; screws 12 x 28 + 5 x 35 = 511.
Same room, walls only, 4 x 12 sheets
Inputs: Ceiling off; 4 x 12 ft
Result: 8 sheets; about 320 screws
333 x 1.10 / 48 = 7.6 -> 8; each sheet spans 10 studs x 4 screws = 40.
Metric room
Inputs: 4 x 3.5 m; 2.4 m walls; 1 door; 2 windows; 1200 x 2400 mm; 400 mm centres
Result: 18 sheets; about 18.4 L compound
Walls 36 - 1.89 - 2.88 = 31.2 m² -> 12 sheets; ceiling 14 m² -> 6.
Limitations
- Doors and windows use one standard size each; very large openings should be measured and the wall reduced by hand.
- Screw counts assume sheets hung across the framing and no adhesive; fire-rated, sound-rated and moisture-area systems have their own fastening schedules.
- Corner bead, setting-type compound for first coats and primer are not included.
Where publishers use it
- Building-supply stores selling drywall by the sheet
- Basement-finishing and garage-conversion guides
- Drywall contractors' estimate request forms
- Home-improvement channels' companion pages
- Landlords budgeting a repair after a leak or remodel
Questions
How many sheets of drywall do I need for a 12 x 12 room?
With 8 ft walls, one door and two windows, the walls are 333 sq ft and the ceiling 144 sq ft. With 10% waste that is 12 sheets of 4 x 8 ft for the walls and 5 for the ceiling - 17 in all.
How many screws per sheet of drywall?
USG specifies screws no more than 16 in apart on walls and 12 in on ceilings. On studs or joists at 16 in centres, a 4 x 8 sheet hung horizontally takes about 28 screws on a wall and 35 on a ceiling.
How much joint compound for drywall?
USG's all-purpose ready-mixed compound covers about 10 gallons per 1,000 sq ft of board for taping and finishing, roughly 41 litres per 100 m². A 477 sq ft room needs about 4.8 gallons.
How much drywall tape do I need?
About 370 ft of paper tape per 1,000 sq ft of board, according to USG - 176 ft for a 477 sq ft room. Buy a full roll; they are 250 or 500 ft.
Should I use longer sheets?
Longer sheets (4 x 10, 4 x 12 ft) mean fewer butt joints to finish but are heavier to lift. In the same room, 4 x 12 sheets cut the wall count from 12 to 8.
Which waste allowance is right?
About 10% for a simple room; 15% where there are many openings, soffits or angles. Offcuts from large walls can often fill above doors and windows.
What thickness of drywall should I use?
In North American homes 1/2 in board is standard on walls, 5/8 in is used on ceilings with wider framing and for fire-rated Type X assemblies, and moisture-resistant board goes in damp areas. Thickness does not change the sheet count, only weight and screw length.
Sources
- Fastener spacing for gypsum board (FAQ) - USG . Screws into wood and steel framing: 12 inches on ceilings and 16 inches for walls.
- Sheetrock All Purpose Joint Compound (ready-mixed) submittal - USG . Coverage approximately 10 gal per 1,000 sq ft of gypsum panels.
- Sheetrock Fast Finish Paper Joint Tape submittal - USG . Coverage approximately 370 ft per 1,000 sq ft of gypsum panels.
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