Drywall Calculator
This professional drywall calculator helps contractors, estimators, and serious DIYers plan wall and ceiling coverage, compute the exact number of sheets, include waste, subtract openings, estimate screws, and project costs—fast, accessible, and accurate.
Project inputs
Add custom opening
Results
Numbers are rounded for practicality. Always verify final quantities against plans, code, and manufacturer instructions.
Authoritative Data Source and Methodology
Primary reference
- Gypsum Association. GA-216-2021 — Application and Finishing of Gypsum Panel Products (2021). Official standard overview: https://www.gypsum.org/product/ga-216-application-and-finishing-of-gypsum-panel-products/
- USG Sheetrock Estimator (accessed 2025). https://www.usg.com/content/usgcom/en/resource-center/tools/sheetrockestimator.html
- CertainTeed Drywall Calculator (accessed 2025). https://www.certainteed.com/drywall-calculator
All calculations are strictly based on formulas and data derived from these sources or standard geometric relationships.
The Formula Explained
A_wall = 2\,(L + W)\,H
A_open = \sum_{i=1}^{n} (w_i \cdot h_i)
A_ceiling =
\begin{cases}
L \cdot W & \text{if ceiling included} \\
0 & \text{otherwise}
\end{cases}
A_{net} = \max\{0,\; A_{wall} - A_{open} + A_{ceiling} \}
A_{wasted} = A_{net} \cdot \left(1 + \frac{p_{waste}}{100}\right)
A_{sheet} = s_w \cdot s_l
N_{wall} = \left\lceil \frac{\max(0, A_{wall} - A_{open}) \cdot (1 + p_{waste}/100)}{A_{sheet}} \right\rceil
\quad
N_{ceil} = \left\lceil \frac{A_{ceiling} \cdot (1 + p_{waste}/100)}{A_{sheet}} \right\rceil
\quad
N_{total} = N_{wall} + N_{ceil}
\text{Screws} \approx r_{wall} \cdot (A_{wall} - A_{open}) + r_{ceil} \cdot A_{ceiling}
Glossary of Variables
- L — room length; W — room width; H — wall height.
- A_wall — total wall surface area before subtracting openings.
- A_open — total area of doors, windows, and custom openings.
- A_ceiling — ceiling area if included.
- A_net — total area to cover after subtracting openings and adding ceiling.
- A_wasted — A_net after applying waste percentage p_waste.
- A_sheet — single board area (width × length).
- N_wall, N_ceil, N_total — boards for walls, for ceiling, and total (rounded up).
- r_wall, r_ceil — screw density (per unit area). Defaults align with GA-216 spacing norms and typical field practice.
How It Works: A Step-by-Step Example
Assume a 12 × 10 ft room with 8 ft walls, include the ceiling, 1 door (3 × 6.67 ft) and 1 window (3 × 4 ft), 10% waste, and 4 × 8 ft boards.
- Walls: A_wall = 2(L + W)H = 2(12 + 10)×8 = 352 sq ft.
- Openings: A_open = 3×6.67 + 3×4 ≈ 32 sq ft.
- Ceiling: A_ceiling = 12×10 = 120 sq ft.
- Net: A_net = 352 − 32 + 120 = 440 sq ft.
- Waste: A_wasted = 440 × 1.10 = 484 sq ft.
- Boards: A_sheet = 32 sq ft; N_total = ceil(484 / 32) = 16 sheets.
- Screws (heuristic): r_wall ≈ 0.90 per sq ft; r_ceil ≈ 1.10 per sq ft → about 0.90×320 + 1.10×120 ≈ 396 screws.
Frequently Asked Questions (FAQ)
What board size should I choose?
Use the longest board that fits and can be handled safely. Longer boards reduce seams but may increase waste in small rooms.
Is 10% waste always enough?
No. It’s a starting point for simple rectangles. Increase to 12–15% for complex layouts, niches, many openings, or angled ceilings.
How are screws estimated?
We use unit-area heuristics derived from GA‑216 spacing norms: roughly 0.90 screws/sq ft for walls and 1.10 screws/sq ft for ceilings at 16 in o.c. framing. For 24 in o.c., the tool adjusts upward.
Can I subtract non-rectangular openings?
Approximate them as rectangles that fully contain the shape. This slightly overestimates the opening but is safe for ordering.
Does drywall thickness change counts?
Not for area or sheet count. Thickness may impact allowable fastener spacing and board selection per code or fire/sound ratings.
How accurate is the cost estimate?
It depends on your unit prices. Input current local prices per sheet and per screw; taxes and accessories are excluded by default.
Can I use metric?
Yes. Toggle Metric and the UI, calculations, and labels switch to meters and square meters. Values are converted automatically.