A 12 × 14 ft room with 8 ft walls, two windows and a door takes 19 sheets of 4 × 8 drywall for the walls and the ceiling: 372 ft² of wall and 168 ft² of ceiling, 540 ft² in all, plus 10 % for waste. Hanging them takes about 580 screws; finishing them, 75 lb of joint compound and 200 ft of tape. The calculator above does the same for a whole room, a single wall, a partition or a ceiling.
How the calculator works
Choose what you are hanging and enter its size. For a room, enter the length, width and wall height, and list the windows and doors; tick the ceiling if it gets drywall too. Then pick the board, the sheet size, the layers and the waste, and the framing spacing. For a wall, partition or ceiling you can add steel framing.
Sheets
The board area is the walls less the openings plus the ceiling; a partition counts both faces, and each extra layer adds the area again. Divide by the sheet area — 32 ft² for 4 × 8, 48 ft² for 4 × 12 — round up and add the waste. Longer sheets leave fewer butt joints, which are the hardest to finish; 4 × 12 sheets on the walls of a 12 ft room cut the joints by a third.
Screws
The IRC fastening schedule (Table R702.3.5) puts screws along every stud or joist under a sheet: 16 in apart on walls and 12 in apart on ceilings for framing at 16 or 24 in. That is about 28 screws per 4 × 8 sheet on a wall and 36 on a ceiling — 580 for the example room.
Mud and tape
| Board area | All-purpose compound | Paper tape |
|---|---|---|
| 500 ft² | 69 lb | 185 ft |
| 1,000 ft² | 138 lb | 370 ft |
| 2,000 ft² | 276 lb | 740 ft |
The figures are USG coverage for three coats of ready-mixed all-purpose compound; a 4.5 gal bucket holds about 62 lb.
Which board
Regular ½ in board covers most walls and ceilings framed at 16 in. Ceilings at 24 in take ⅝ in to keep from sagging. ⅝ in Type X is fire-rated, required where a garage meets the house. Moisture-resistant board belongs in bathrooms and laundry rooms but not inside a shower, which needs cement board.
Common mistakes
- Forgetting the ceiling. In a 12 × 14 ft room it is almost a third of the board.
- Deducting every opening in full. Small windows mostly become offcuts; keep the waste at 10–15 %.
- Hanging walls first. Hang the ceiling first so the wall sheets hold its edges up.
For the paint that goes on next, use the Paint Calculator; for the framing behind it, the Wall Framing Calculator.