Drywall / Plasterboard Calculator
Calculate how many plasterboard sheets you need for walls and ceilings. Accounts for openings like doors and windows, plus wastage for cuts.
When to Use
- Domestic wall lining (single or double layer)
- Ceiling installations
- Stud wall construction
- Patching and repair work
Standard Sheet Sizes
| Application | Size | Thickness |
|---|---|---|
| Standard Walls | 1200mm × 2400mm | 12.5mm |
| Ceilings | 1200mm × 2400mm | 9.5mm |
| Tall Ceilings | 1200mm × 2700mm | 12.5mm |
| Heavy Duty | 1200mm × 2400mm | 15mm |
Additional Materials Needed
- Drywall screws: approximately 40 per sheet
- Joint tape: approximately 3 metres per sheet
- Joint compound: approximately 1kg per 3-4 m²
- Corner bead for external corners
Tips
- Allow 10-15% wastage for cutting around openings
- Measure and subtract doors, windows, and large openings
- Plan sheet layout to minimize butt joints
- Stagger joints in double-layer applications
CACalifornia Building Code (Title 24)
References & Sources
Standards Cited
- ASTM C1396 — ASTM C1396: Standard Specification for Gypsum Board
Defines standard drywall sheet sizes, thicknesses, and material specifications for North American construction - GA-216 — Gypsum Association GA-216: Application and Finishing of Gypsum Panel Products
Provides guidance on drywall installation, fixing centres, and joint treatment
Formulas Used
- Wall Area:
wallArea = wallLength x wallHeight
Source: Standard geometry - Net Area:
netArea = wallArea - openingArea
Source: GA-216 - Sheets Required:
sheets = ceil(netArea / sheetArea)
Source: GA-216 - Sheet Area:
sheetArea = (sheetWidth / 1000) x (sheetHeight / 1000)
Source: ASTM C1396 — Standard sheet: 4x8 ft (1219x2438mm) = 2.97 m² - Screws per Sheet:
screws = sheetsRequired x fixingsPerSheet x 1.1
Source: GA-216 — Default 40 fixings per sheet with 10% extra; typical fixing centres 300mm at edges, 300mm in field - Joint Tape:
jointTape = sheetsRequired x 3m
Source: GA-216 — Approximately 3m of joint tape per standard sheet
Key Assumptions
- Standard drywall sheet size is 4x8 ft (1219x2438mm); also available in 4x10 and 4x12 — ASTM C1396 / GA-216
- Standard wall board thickness is 1/2" (12.7mm); ceiling/fire-rated is 5/8" (15.9mm) — ASTM C1396
- Default 40 fixings (screws) per standard sheet at recommended centres — GA-216
- Default 10% wastage for cuts and fitting around openings — Industry standard practice