Drywall is counted by board area: the walls (and ceiling) you cover, minus doors and windows, times the number of layers and faces, divided by the area of one sheet, plus an allowance for cuts. For a new stud wall the calculator also counts the studs and the track.
Example: a 12 × 14 ft room with 8 ft ceilings. The walls are 2 × (12 + 14) × 8 = 416 ft². With 10% extra that is 457.6 ft², or 15 sheets of 4 × 8 ft (32 ft² each) – or 10 sheets of 4 × 12 ft. In metric, a 3.5 × 4 m room with 2.5 m walls has 37.5 m² of wall: 15 sheets of 1,200 × 2,400 mm.
Sheets for common rooms (walls only, and with the ceiling)
8 ft walls, no openings taken off, 10% extra.
| Room | Wall area | 4 × 8 ft sheets | 4 × 12 ft sheets | Walls + ceiling, 4 × 8 | Walls + ceiling, 4 × 12 |
|---|---|---|---|---|---|
| 10 × 10 ft | 320 ft² | 12 | 8 | 15 | 10 |
| 12 × 12 ft | 384 ft² | 14 | 9 | 19 | 13 |
| 12 × 14 ft | 416 ft² | 15 | 10 | 21 | 14 |
| 14 × 16 ft | 480 ft² | 17 | 11 | 25 | 17 |
| 20 × 20 ft | 640 ft² | 23 | 15 | 36 | 24 |
2.5 m walls, 10% extra:
| Room | Wall area | 1,200 × 2,400 mm | 1,200 × 2,700 mm | Walls + ceiling, 2,400 | Walls + ceiling, 2,700 |
|---|---|---|---|---|---|
| 3 × 3 m | 30.0 m² | 12 | 11 | 15 | 14 |
| 3.5 × 4 m | 37.5 m² | 15 | 13 | 20 | 18 |
| 4 × 5 m | 45.0 m² | 18 | 16 | 25 | 23 |
| 5 × 6 m | 55.0 m² | 22 | 19 | 33 | 29 |
Sheet sizes around the world
| Market | Width | Common lengths | Common thickness |
|---|---|---|---|
| US, Canada | 4 ft (1,219 mm) | 8, 9, 10, 12 ft (16 ft to order) | 1/2 in walls, 5/8 in ceilings and fire walls |
| UK, Ireland | 1,200 mm | 2,400 and 2,700 mm | 12.5 mm, 15 mm |
| Europe | 1,200 mm (some 600 or 625 mm) | 2,000–3,000 mm | 12.5 mm |
| Australia, New Zealand | 1,200 mm (some 1,350) | 2,400–6,000 mm | 10 mm walls, 13 mm ceilings |
The calculator lists the most common sizes; for others, compare the area of your sheet with the closest one on the list.
A new stud wall
For a partition, choose “A new stud wall”: the board area counts both faces, and the calculator adds the studs (wall length ÷ spacing, plus one) and the top and bottom track. A 12 ft wall at 16 in centers takes 10 studs; at 24 in, 7. A 4 m wall at 600 mm takes 8 studs, and 11 at 400 mm. Add studs for door openings, corners and anything you will hang (cabinets, a TV).
US framing is on 16 or 24 in centers, matched to the 48 in sheet; metric framing is on 400 or 600 mm centers, matched to the 1,200 mm sheet. Keep the system your sheets are made for, so every edge lands on a stud.
Screws and tape
- Screws: about one per square foot of board (32 per 4 × 8 ft sheet), from screw spacing of 16 in on walls and 12 in on ceilings. Fire-rated and sound walls use the spacing of their tested system.
- Joint tape: USG’s own figure is about 370 ft of tape per 1,000 ft² of board (112 m per 93 m²); the calculator uses it.
- Joint compound: the bucket gives its coverage; it depends a lot on how many coats and how smooth a finish you want.
Once zet4u is saved on your phone, the calculator works offline – in a basement or on a site without reception.
Frequently asked questions
How many sheets of drywall for a 12 × 12 room?
The four walls of a 12 × 12 ft room with 8 ft ceilings are 384 ft²: 12 sheets of 4 × 8 ft, or 14 with 10% extra for cuts. Doors and windows reduce it a little, but most hangers keep the extra anyway. Add the ceiling (144 ft²) and it is 19 sheets.
Should I hang drywall horizontally or vertically?
On walls up to 8 ft (2.4 m) high, longer sheets hung horizontally leave fewer joints to tape, and the joints sit at a comfortable working height. Taller walls and commercial jobs are often hung vertically. The number of sheets is about the same either way.
How many screws per sheet of drywall?
About 32 for a 4 × 8 ft sheet: screws 16 in apart along each stud on walls and 12 in apart on ceilings, roughly one per square foot of board. Screw boxes give a count or a weight; the count is the number to compare.
What is the difference between drywall and plasterboard?
None, apart from the word: drywall, gypsum board, wallboard and Sheetrock (a brand) in North America, plasterboard in the UK, Ireland, Australia and New Zealand, Gyproc or Rigips in parts of Europe. The sizes differ: 4 ft (1,219 mm) wide in the US and Canada, 1,200 mm almost everywhere else.
Sources
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