DRYWALL CALCULATOR
How it works
40 linear feet of wall at 8 feet high, in 4 × 8 sheets, with no waste added.
- Area: 40 ft × 8 ft = 320 ft².
- Sheets: 320 ÷ 32 = 10 sheets exactly. Any fraction rounds up — there is no half sheet at the counter.
- Screws: 10 sheets × 32 = 320 screws.
- Compound: 10 × 4.5 lb = 45 lb.
- Tape: 10 × 40 ft = 400 linear feet.
10 sheets of 4 × 8 drywall, 320 screws, 45 lb of compound and 400 ft of tape.
Constants
| Constant | Value |
|---|---|
| 4 × 8 sheet coverage | 32 ft² |
| 4 × 12 sheet coverage | 48 ft² |
| Screws per sheet | 32 |
| Joint compound per sheet | 4.5 lb |
| Joint tape per sheet | 40 ft |
SOURCE — a 4 ft × 8 ft sheet covers 32 ft². Geometry.
SOURCE — a 4 ft × 12 ft sheet covers 48 ft². Geometry.
SOURCE — USG Gypsum Construction Handbook: screws at 12" on centre in the field and 8" at the edges work out to ≈32 per 4×8 sheet on 16" framing.
SOURCE — USG: ≈0.14 lb of ready-mixed joint compound per ft² over three coats — about 4.5 lb per 4×8 sheet.
SOURCE — USG: ≈40 linear ft of joint tape per 4×8 sheet of board.
Quick answers
320 square feet of wall takes 10 sheets of 4 × 8 drywall, 320 screws, 45 lb of joint compound and 400 feet of tape.
A 4 × 8 sheet covers 32 square feet and a 4 × 12 covers 48. Divide your total area by the sheet coverage and always round up.
Budget about 32 screws per 4 × 8 sheet — 12 inches on centre in the field and 8 inches at the edges over 16-inch framing.
Joint compound runs about 0.14 lb per square foot over three coats, which is roughly 4.5 lb per 4 × 8 sheet.
Larger 4 × 12 sheets cut the number of butt joints on a long wall, which is why finishers prefer them even though they are much harder to lift.
FAQ
How many sheets of drywall do I need?
Divide the total surface area by 32 for 4 × 8 sheets, or 48 for 4 × 12, and round up. Forty feet of 8-foot wall is 320 ft², which is exactly 10 sheets of 4 × 8.
Should I subtract windows and doors?
Only for large openings. Most hangers sheet straight over a standard door or window and cut the opening out afterwards, so the material is used either way. Subtract openings bigger than about 30 square feet.
How many screws per sheet of drywall?
About 32 for a 4 × 8 sheet on 16-inch framing — 12 inches on centre in the field, 8 inches along the edges. Ceilings take more, closer to 8 inches throughout.
How much joint compound do I need?
Roughly 4.5 lb per 4 × 8 sheet for a standard three-coat finish, which is about 0.14 lb per square foot. A level 5 finish with a skim coat takes noticeably more.
4 × 8 or 4 × 12 sheets?
4 × 12 sheets eliminate butt joints on walls up to 12 feet, which makes finishing faster and flatter. They weigh close to 80 lb each, so they are a two-person lift and will not fit in most cars.
How much waste should I allow?
Ten percent is typical for a room with normal openings, and more for a space with many corners, angles or soffits. Offcuts from around openings often serve elsewhere, so careful planning reduces this.