How to use this drywall calculator
- Measure the room length, width and ceiling height.
- Choose whether to include the ceiling.
- Pick the sheet size you plan to hang.
- Keep 10% extra for cuts.
Example
A 12 × 10 ft room with 8 ft walls has 472 sq ft (43.9 m²) of walls and ceiling. With 4 × 8 ft sheets and 10% waste you need 17 sheets.
What to know before you buy
Drywall thickness
1/2 inch drywall is standard for walls in homes. 5/8 inch (often fire-rated Type X) is used on ceilings, garages walls shared with the house and where codes require fire resistance. 1/4 inch sheets are for curved walls or covering existing surfaces.
Finishing supplies
For every 1,000 sq ft of drywall, plan roughly 370 ft of tape, 140 lb of joint compound (about 3 buckets of premixed) and 1,000–1,500 screws. Corner bead is needed on every outside corner.
4 × 8 ft drywall sheets for walls and ceiling (8 ft walls, 10% waste)
| Room size | Sheets needed | Surface area |
|---|---|---|
| 10 × 10 ft | 15 | 420 sq ft (39 m²) |
| 10 × 12 ft | 17 | 472 sq ft (43.9 m²) |
| 12 × 12 ft | 19 | 528 sq ft (49.1 m²) |
| 12 × 16 ft | 22 | 640 sq ft (59.5 m²) |
| 14 × 16 ft | 25 | 704 sq ft (65.4 m²) |
| 20 × 20 ft | 36 | 1,040 sq ft (96.6 m²) |
Formula
Sheets = (wall area + ceiling area) × (1 + waste) ÷ area of one sheet.
Tips from the pros
- Hang ceiling sheets first, then the walls, with the top wall sheet pushed tight to the ceiling.
- Use 12 ft sheets on long walls to reduce butt joints and taping work.
- Use moisture-resistant board in bathrooms and cement board behind tile in showers.
Common mistakes to avoid
- Placing joints right at the corners of doors and windows, where cracks tend to appear.
- Forgetting that ceilings usually need 5/8 in board or closer framing to avoid sagging.
Frequently asked questions
How many sheets of drywall for a 12×12 room?
With 8 ft walls and the ceiling, about 18–20 sheets of 4×8, including waste.
Should I subtract doors and windows?
Most pros don't, because the pieces cut out are rarely usable elsewhere.
How many square feet is a sheet of drywall?
A 4 × 8 ft sheet covers 32 sq ft, a 4 × 10 ft sheet 40 sq ft and a 4 × 12 ft sheet 48 sq ft.
How much does a sheet of drywall weigh?
A standard 1/2 inch 4 × 8 sheet weighs about 50–55 lb; lightweight versions are around 40 lb, and 5/8 inch sheets about 70 lb.