Drywall Calculator
Enter room dimensions and door/window areas to instantly compute wall area, required drywall board count and cost. Essential for partition walls and false ceilings.
輸入資料
計算結果
重點速覽：The drywall calculator is a 'wall area ÷ board area' model. First get the four-wall area from room length/width/height, subtract door/window openings for the net boarding area; boards needed = net area × (1+waste) ÷ single board area, rounded up; total cost = boards × price per board. Board area is typically based on 1.2m×2.4m (~2.88m²), adjustable to the actual board on site.
計算公式
Wall area A = 2 × (length + width) × height
Net area = A − door area − window area
Board area = board width × board length
Boards N = ⌈ net area × (1 + waste%) ÷ board area ⌉
Total cost = N × price per board
Example: 5m×4m×2.5m room, minus 3.1m² openings → 45m²−3.1m², 1.2m×2.4m board at 10% waste ≈ 17 boards.
$$A = 2(L+W)H$$$$A_{net} = A - A_d - A_w$$$$A_b = w_b \times l_b$$$$N = \left\lceil \frac{A_{net}(1+w\%)}{A_b} \right\rceil$$使用說明
- Enter room length, width and wall height.
- Enter door and window areas to deduct.
- Select the actual board size (default 1.2m×2.4m).
- Set the waste percentage (default 10%).
- Enter price per board if costing.
- The tool outputs wall area, net area and boards needed.
Common gypsum board sizes and area
| Board size | Area (approx) | For 10m² wall |
|---|---|---|
| 1.2m × 2.4m (4×8 ft) | 2.88 m² | ≈ 4 boards |
| 1.22m × 2.44m (4×8 ft imperial) | 2.98 m² | ≈ 4 boards |
| 1.2m × 3m | 3.6 m² | ≈ 3 boards |
Theoretical values without waste; order ~10% extra in practice.
理財情境案例
Home partition
Living room partition, 5m×4m, wall height 2.5m, openings 3.1m².
Wall area 45m², net boarding 41.9m².
1.2m×2.4m board at 10% waste ≈ 17 boards.
Office partitions
Several 3m×3m partitions, each with a 1.6m² door.
Each wall 30m², net 28.4m².
≈ 11 boards each; multiply by room count for the total.
False ceiling
Gypsum false ceiling: area = length × width of the ceiling.
Set length/width to ceiling size and wall height to 0 to get the board count directly.
10% waste covers cutting and offcuts.
常見問題
How is wall area computed?
Wall area = 2 × (room length + room width) × wall height — the sum of the four walls. For a partial wall, set length/width to that wall segment.
Why deduct door/window areas?
Door and window openings need no boarding; deducting them gives the actual usage and avoids overestimating boards. A standard door ~1.6m², common window ~1–2m².
What waste percentage to use?
Cutting, breakage and offcuts for gypsum board are usually ~10%. For irregular walls or pattern matching, raise to 15%.
How much does a 1.2m×2.4m board cover?
About 2.88m² each. A 10m² wall needs ~4 boards (with waste).
Gypsum board vs cement board?
Gypsum (grey board) is common for dry-area partitions and false ceilings; fibre-cement board is more water-resistant for wet areas like kitchens and bathrooms.
相關工具
參考資料
Content reviewed by the Hong Kong Calculator science team. Wall area, board count and waste formula verified against Gypsum Association technical data.