Drywall calculator
Enter the room's length, width and wall height, the doors and windows, and the sheet size. The calculator draws the sheets on each wall and the ceiling, counts them, and works out the joint compound, tape and screws from the manufacturers' estimating figures.
Drywall calculator
Each 3 ft × 6 ft 8 in (20 ft²).
Each 3 × 5 ft (15 ft²).
For cut-outs, offcuts and breakage. USG's own estimator adds none; type your own.
Sheets to buy
12 sheets
- Joint compound
- 5.3 gal
- Paper tape
- 198 ft
- Screws
- 505
About 2 × 4.5 gal pails of all-purpose compound and 1 × 250 ft roll of tape, at USG's coverage of the board installed.
Walls, unfolded, in sheets
Sheets by surface
- Wall A1.917%
- Wall B1.715%
- Wall C218%
- Wall D218%
- Ceiling3.531%
The formula
- Each wall: its length × the wall height, less the doors and windows on it (a door 3 ft × 6 ft 8 in, a window 3 × 5 ft; in metric 0.9 × 2.1 m and 1.2 × 1.2 m).
- The ceiling, if you include it: length × width.
- Sheets: each surface's area × (1 + your waste allowance) ÷ the area of one sheet (32 ft² for 4 × 8, 40 ft² for 4 × 10, 48 ft² for 4 × 12), added up and rounded up to whole sheets.
- Tape and compound: the board installed (the area covered: the waste allowance and the rest of the last sheet are offcuts and take none) × 370 ft of tape and 10 gal of ready-mixed compound per 1,000 ft².
- Screws: 875 per 1,000 ft² of wall board and 1,094 per 1,000 ft² of ceiling board, installed.
Worked example
A 14 × 12 ft room with 8 ft walls, one door and two windows, walls and ceiling, in 4 × 12 ft sheets. The walls are 2 × (14 + 12) × 8 = 416 ft², less 20 ft² for the door and 30 ft² for the windows: 366 ft². The ceiling is 168 ft². That is 534 ft², and 534 ÷ 48 = 11.1, so 12 sheets. With a 10% allowance typed in, 534 × 1.1 ÷ 48 = 12.2, so 13 sheets: 624 ft² of board. Tape, compound and screws go on the 534 ft² hung, not on the offcuts: 534 × 370 ÷ 1,000 = 198 ft of tape (one 250 ft roll), 5.3 gal of compound (two 4.5 gal pails) and 505 screws (875 per 1,000 ft² on the 366 ft² of walls, 1,094 on the 168 ft² of ceiling).
| Room | Doors, windows | Area | 4 × 8 sheets | 4 × 12 sheets | Compound | Tape | Screws |
|---|---|---|---|---|---|---|---|
| 10 × 10 ft | 1, 1 | 385 ft² | 13 | 9 | 3.9 gal | 142 ft | 359 |
| 10 × 12 ft | 1, 1 | 437 ft² | 14 | 10 | 4.4 gal | 162 ft | 409 |
| 12 × 12 ft | 1, 2 | 478 ft² | 15 | 10 | 4.8 gal | 177 ft | 450 |
| 12 × 14 ft | 1, 2 | 534 ft² | 17 | 12 | 5.3 gal | 198 ft | 505 |
| 14 × 16 ft | 1, 2 | 654 ft² | 21 | 14 | 6.5 gal | 242 ft | 622 |
| 16 × 20 ft | 2, 3 | 811 ft² | 26 | 17 | 8.1 gal | 300 ft | 780 |
Compound, tape and screws follow the area covered, so they are the same whichever sheet you hang. In metric, a 4 × 3 m room with 2.5 m walls, a door and a window, walls and ceiling, is 43.7 m²: 16 sheets of 1.2 × 2.4 m, about 18 litres of compound and 53 m of tape.
Before you order
- Longer sheets mean fewer joints. A 4 × 12 sheet across a 12 ft wall leaves no butt joint to tape; the table shows 12 of them doing the work of 17 smaller sheets.
- Doors and windows: the calculator takes them off, as many estimators do for a whole room. Small openings are often cut out of a full sheet, so a room with many of them needs a bigger allowance.
- Wet areas: behind tile in a tub or shower, the IRC requires a tile backer rather than paper-faced drywall (R702.4.2). Take those walls out of the count.
- Ceilings: heavier or longer sheets are hard to lift overhead; many people hire help or a drywall lift for the ceiling.
Every room at once
FloorGen's Schedules and budget panel (in the account menu) gives each room's wall area net of its doors and windows and its floor area, which is the ceiling. It does not count sheets: divide by the sheet's area as above. How much drywall do I need? works a whole garage conversion through.
Questions
How many sheets of drywall do I need for a 12 × 12 room?
With 8 ft walls, a door and two windows, the walls are 334 ft² and the ceiling 144 ft²: 478 ft². That is 10 sheets of 4 × 12 or 15 sheets of 4 × 8, before any waste allowance.
How much joint compound do I need?
USG gives about 10 gallons of ready-mixed all-purpose compound per 1,000 ft² of board, so a 4.5 gallon pail covers roughly 450 ft². A 12 × 14 ft room with its ceiling, 534 ft² of board, takes about 5.3 gallons.
How much drywall tape per sheet?
USG's figure is about 370 ft of paper tape per 1,000 ft² of board: roughly 12 ft per 4 × 8 sheet and 18 ft per 4 × 12 sheet.
How many screws per sheet of drywall?
USG's handbook gives about 875 screws per 1,000 ft² at 16 in spacing (walls) and 1,094 at 12 in (ceilings), with framing 16 in on centre: about 28 a sheet on a wall and 35 on a ceiling for 4 × 8 board.
Should I subtract doors and windows?
For a whole room it is reasonable for doors and large windows. Small openings usually come out of a sheet you buy anyway, so if you keep them in, you have a built-in allowance.