Drywall calculator
Give the room size and the sheet size you can get into the house. The calculator counts sheets for the walls and optional ceiling, then estimates the joint compound, tape, and screws to finish them.
How the drywall calculator works
The calculator totals the wall area from the room perimeter and height, subtracts standard allowances for doors and windows, and adds the ceiling if you include it. Dividing the total by the area of one sheet gives the sheet count, with a waste factor for cuts around outlets and odd corners.
Finishing materials follow industry rules of thumb published by USG and other manufacturers: about 0.053 pounds of ready-mixed joint compound per square foot of drywall, 37 feet of tape per 100 square feet, and 32 screws per 4 × 8 sheet when fastening 12 inches on center in the field and 8 inches on the edges.
Formula
area = 2 × (length + width) × height − openings + ceiling
sheets = area × (1 + waste) ÷ sheet area, rounded up
Example: a 12 × 14 ft room with 8 ft ceilings has 416 sq ft of wall, minus 51 sq ft for a door and two windows, plus a 168 sq ft ceiling, for 533 sq ft. With 10 percent waste that is 586 sq ft, or 19 sheets of 4 × 8. Finishing takes about 28 lb of mud, 200 ft of tape, and 600 screws.
Choosing sheet size and thickness
- 4 × 8 sheets fit through most doorways and are easiest to handle alone. They create more seams to tape.
- 4 × 12 sheets hung horizontally span most walls with no vertical seams, which saves finishing time. Two people and a clear path are required.
- 1/2 inch is standard for walls and ceilings on 16 in framing. 5/8 inch is used for ceilings on 24 in framing, for fire-rated walls, and for garages attached to living space.
- Moisture-resistant green or purple board goes in bathrooms; cement board goes behind tile in showers.
- After it is finished, the paint calculator picks up where this one leaves off. New drywall needs primer.
Common questions
How many sheets of drywall do I need for a 12x12 room?
About 18 sheets of 4 × 8 for the walls and ceiling with 8 ft ceilings, after subtracting a door and a window and adding 10 percent waste. Walls alone take about 13 sheets.
How much joint compound do I need per sheet of drywall?
Roughly 1.7 pounds of ready-mix all-purpose compound per 4 × 8 sheet, or one 4.5 gallon bucket for every 35 sheets. Add about 20 percent if you are also skim coating or using a lot of corner bead.
How many screws per sheet of drywall?
About 32 screws for a 4 × 8 sheet on 16 in framing, spaced every 12 inches in the field and 8 inches along the edges. A 1 lb box holds roughly 300 screws, enough for 9 sheets.
Should drywall be hung vertically or horizontally?
Horizontally on residential walls under 8 ft 1 in. It puts the long seam at a comfortable working height and cuts total seam length by about 25 percent compared with vertical hanging. Fire-rated commercial walls often require vertical.