Quick answer: Divide the wall (and ceiling) area by the area of one sheet and add 10% for waste. A 12 × 12 ft room with 8 ft walls needs 14 sheets of 4 × 8 drywall for the walls, or 19 sheets including the ceiling.
Whether you are finishing a basement, building an addition or replacing damaged walls, the first question is how many sheets of drywall to buy. Here are two ways to calculate it.
Method 1: By Area
Sheets = (Wall area + Ceiling area) × 1.10 ÷ Sheet area
A 4 × 8 sheet covers 32 sq ft, a 4 × 10 covers 40 sq ft and a 4 × 12 covers 48 sq ft. For the 12 × 12 room: walls are 384 sq ft, plus 10% = 422 sq ft, divided by 32 = 13.2, so 14 sheets.
Method 2: By Wall Length
Installers often hang sheets horizontally. On an 8 ft wall, two 4 ft sheets stacked cover the full height, so the sheets needed per wall are the wall length divided by the sheet length, times two. A 12 ft wall takes 1.5 sheets of 8 ft per row, so 3 sheets; four walls need 12 sheets, plus extra for waste. Using 12 ft sheets on a 12 ft wall means just one sheet per row and fewer joints to finish.
Skip the math: enter the room size, openings and sheet size to get sheets, screws, joint compound and tape. Open the free Drywall Calculator →
Drywall Sheets by Room Size
4 × 8 ft sheets, 8 ft walls, 10% waste, openings not subtracted:
| Room size | Walls only | Walls + ceiling |
|---|---|---|
| 10 × 10 ft | 11 | 15 |
| 10 × 12 ft | 13 | 17 |
| 12 × 12 ft | 14 | 19 |
| 12 × 14 ft | 15 | 21 |
| 14 × 16 ft | 17 | 25 |
| 16 × 20 ft | 20 | 31 |
| 20 × 20 ft | 22 | 36 |
Doors and windows reduce these numbers a little, but many installers keep them in the count because sheets are cut around openings and the offcuts are often too small to reuse.
Other Materials
| Item | Rule of thumb |
|---|---|
| Drywall screws | About 32 per 4 × 8 sheet on walls (roughly 1 per sq ft) |
| Joint compound | About 140 lb per 1,000 sq ft |
| Paper joint tape | About 370 ft per 1,000 sq ft |
| Corner bead | One length per outside corner |
Choosing Sheet Size and Thickness
- 4 × 8 sheets are easiest to carry and fit in most vehicles.
- 4 × 12 sheets mean fewer seams on long walls, but need two people.
- ½ inch is standard for walls; ⅝ inch is used for ceilings and fire-rated walls.
- Use moisture-resistant board in bathrooms and laundry rooms.
Metric Example
A 4 × 3 m room with 2.4 m walls has 33.6 m² of wall. With 10% waste that is 37 m², or 13 boards of 1.2 × 2.4 m (2.88 m² each).
Once the walls are finished, see how much paint you need.
Frequently Asked Questions
How many sheets of drywall do I need for a 10×10 room?
With 8 ft walls, a 10 × 10 room has 320 sq ft of wall. With 10% waste you need 11 sheets of 4 × 8 drywall, or 15 including the ceiling.
Is it better to hang drywall horizontally?
Usually yes. Horizontal hanging on walls typically gives fewer seams, and the seams are at a comfortable height for taping.
How many screws per sheet of drywall?
About 32 screws per 4 × 8 sheet on walls with studs 16 inches apart. Ceilings often need a few more.
Related Guides
- How to Measure a Room for Flooring (Step-by-Step)
- How Many Tiles Do I Need for a Bathroom Floor or Shower?
- How Much Paint Do I Need for a Room? (Chart by Room Size)
Try the free Drywall Calculator or browse all home improvement calculators.