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.
Input Data
Results
At a glance: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.
Formula
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.
$$A = 2(L+W)H$$$$A_{net} = A - A_d - A_w$$$$A_b = w_b \times l_b$$$$N = \left\lceil \frac{A_{net}(1+w\%)}{A_b} \right\rceil$$How to Use
- 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.
Case Studies
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.
FAQ
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.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.