Enter the size of the room and the number of doors and windows. The calculator gives the sheets of drywall for the walls and ceiling in 4 × 8, 4 × 10 or 4 × 12 ft sheets, and an estimate of the screws.
How to use the drywall calculator
- Enter the length and width of the room and the wall height.
- Choose whether to include the ceiling.
- Enter the number of doors and windows; each standard door deducts 21 ft² and each window 15 ft². For big openings, enter fewer and reduce the area yourself.
- Pick the sheet size and keep about 10% waste for cuts.
Drywall formulas
Wall area = 2 × (length + width) × height − doors × 21 − windows × 15 Ceiling area = length × width Sheets = area × (1 + waste %) ÷ sheet area, rounded up, walls and ceiling separately Screws per sheet = framing members crossed × screws per member
Sheet areas are 32 ft² for 4 × 8, 40 ft² for 4 × 10 and 48 ft² for 4 × 12. Walls and ceilings are counted separately because offcuts from one rarely fit the other. The screw estimate follows the spacing described in Walls & Ceilings: screws 12 in apart on ceilings, 16 in apart on walls framed at 16 in centers and 12 in apart on walls framed at 24 in. Fire-rated and multi-layer assemblies follow their own tested patterns.
Worked example: a 14 × 12 ft bedroom, 8 ft walls
- Walls: 2 × (14 + 12) × 8 = 416 ft², minus one door (21) and one window (15) = 380 ft².
- Wall sheets, 4 × 8 with 10% waste: 380 × 1.10 ÷ 32 = 13.06, so 14 sheets.
- Ceiling: 14 × 12 = 168 ft²; 168 × 1.10 ÷ 32 = 5.78, so 6 sheets.
- Total: 20 sheets and about 602 screws.
Sheets for common rooms
One door, one window, ceiling included, 10% waste:
| Room | Area (ft²) | 4 × 8 sheets | 4 × 12 sheets |
|---|---|---|---|
| 10 × 10 ft, 8 ft walls | 384 | 14 | 10 |
| 12 × 12 ft, 8 ft walls | 492 | 17 | 12 |
| 14 × 12 ft, 8 ft walls | 548 | 20 | 13 |
| 16 × 14 ft, 8 ft walls | 668 | 24 | 17 |
| 20 × 16 ft, 9 ft walls | 932 | 33 | 23 |
Which sheet size should I use?
Longer sheets mean fewer joints to tape and finish, so 4 × 12 sheets are common on walls in new construction. They are heavy and awkward, though; 4 × 8 sheets are easier to carry up stairs and through doors, and suit small rooms and repairs.
Tips for buying drywall
- Use moisture-resistant board in bathrooms. Check your local code for wet areas.
- Buy a sheet or two extra. Breakage in transport and mis-cuts happen on every job.
- Hang ceilings first. The wall sheets then hold up the ceiling edges.
- Framing a new wall? The stud calculator counts studs and plates.
Questions
How many sheets of drywall for a 12 × 12 room?
About 17 sheets of 4 × 8 with 8 ft walls, one door, one window, the ceiling and 10% waste.
How many square feet is a sheet of drywall?
32 ft² for 4 × 8, 40 ft² for 4 × 10 and 48 ft² for 4 × 12.
How many screws per sheet of drywall?
About 28 for a 4 × 8 sheet on walls with studs at 16 in, and about 36 on a ceiling with joists at 16 in, using the spacing above.
Should I subtract doors and windows?
Yes for doors and large windows. Small openings are often left in as extra for waste.
Sources
- All Things Gypsum: Attachment of Gypsum Board, Walls & Ceilings, Aug 1, 2006.
Used for: Screw spacing for single-layer gypsum board: 12 in on ceilings; 16 in on walls at 16 in centers, 12 in at 24 in centers. - NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Exact inch and foot definitions.