The Gypsum Ceiling Calculator estimates the materials for a gypsum board (plasterboard) ceiling: number of boards, metres of brandering or battens, screws and joint tape.
Boards are calculated from the ceiling area divided by one board’s area plus waste. Brandering runs the length of the room at your chosen spacing, screws are counted per board, and joint tape is estimated from the board joints and perimeter.
Gypsum Board Ceiling Calculator
Gypsum / plasterboard ceiling boards, screws, joint tape and brandering (battens) for a room.
Formula
- Boards: N = ⌈L × W ÷ (board width × board length) × (1 + waste)⌉
- Brandering: (⌈W ÷ spacing⌉ + 1) × L
- Screws: N × screws per board
- Joint tape ≈ A ÷ board width + A ÷ board length + 2 × (L + W)
Where L, W = room length and width, A = L × W.
How the Calculation Works
Step 1: Ceiling area = length × width.
Step 2: Divide by the board area and add waste for the board count.
Step 3: Rows of brandering = width ÷ spacing, rounded up, plus one; each row is the room length.
Step 4: Joint tape approximates the long joints, end joints and the wall-ceiling perimeter.
Variables Explained
| Input | Meaning |
|---|---|
| Board width, length | Size of one board, e.g. 1.2 × 2.4 m |
| Brandering / batten spacing | Centre-to-centre spacing of the timber or metal battens the board fixes to |
| Screws per board | Per your board manufacturer’s fixing pattern |
| Waste allowance | Extra boards for cuts and damage |
Example Calculation
Given: 5 × 4 m room, 1.2 × 2.4 m boards, 400 mm brandering, 32 screws per board, 10% waste
- Area = 20 m²; board area = 2.88 m²
- Boards = 20 ÷ 2.88 × 1.10 = 7.64 → 8 boards
- Brandering = (4 ÷ 0.4 + 1) × 5 = 11 × 5 = 55 m
- Screws = 8 × 32 = 256
- Joint tape ≈ 16.7 + 8.3 + 18 = 43 m
Material Estimation Notes
- Board thickness, batten spacing and screw spacing should follow the board manufacturer’s system guide.
- Battens are usually bought in fixed lengths — divide the metres by one length and round up.
- Cornice, jointing compound and ceiling hangers are not included.
- Joint tape is approximate; the actual length depends on the board layout.
Units and Dimensions
The defaults are metric. For imperial, enter feet: a 4 × 8 ft drywall sheet covers 32 ft², and batten spacing of 16 in = 1.333 ft.
Frequently Asked Questions
How many gypsum boards do I need for a ceiling?
Ceiling area ÷ board area, plus waste. A 20 m² ceiling with 2.88 m² boards needs 7 boards before waste.
What is brandering?
Brandering is the timber battens fixed under the roof trusses or joists that ceiling boards are screwed to.
How much brandering do I need?
(Room width ÷ spacing, rounded up, + 1) × room length.
How many screws per gypsum board?
It depends on board size and fixing spacing; use the manufacturer’s fixing guide.
Is gypsum board the same as drywall?
Yes — gypsum board, plasterboard and drywall refer to the same type of panel.