Drywall Calculator
Enter room dimensions or a measured board area, choose sheet size and waste, and get sheets to order plus rough fastener, tape, and mud quantities.
Calculate
Calculate
Measurements convert when you switch units
Result
The formula
For a rectangular room, wall area = 2×(L+W)×H. Add ceiling (L×W) when hanging it, subtract door/window deductions and any extra openings, then apply waste and divide by sheet coverage. Accessory estimates use common field rules of thumb from the net board area.
Worked example
- Room 5 m × 4 m × 2.4 m → walls = 2×(5+4)×2.4 = 43.2 m²; ceiling = 20 m²
- 1 door (2.0 m²) + 1 window (1.4 m²) → net = 43.2 + 20 − 3.4 = 59.8 m²
- Sheet 120 cm × 240 cm = 2.88 m²; with 10% waste → ceil(65.78 ÷ 2.88) = 23 sheets
Result: Order 23 sheets (plus screws, tape, and compound estimates)
How drywall quantity is calculated
The calculator converts room geometry (or a direct area entry) into net board area, adds a waste allowance for cuts and breakage, then packs that demand into whole sheets and rough finishing materials.
Room takeoff vs measured area
Room mode builds walls from perimeter × height and optionally adds the ceiling footprint. Area mode is for irregular spaces you already measured as combined rectangles.
Standard planning deductions are about 2.0 m² (21 ft²) per door and 1.4 m² (15 ft²) per window. Use Extra openings for closets, large glazed walls, or openings you want to subtract yourself.
Sheet size and waste
Coverage is sheet length × width. Common North American boards are 4×8 ft (48×96 in); many European markets use 1200×2400 mm panels. Longer sheets reduce butt joints on tall walls but are heavier to hang.
About 10% waste suits typical residential rooms with openings. Simple rectangular walls with few cuts can use 5–8%; vaulted ceilings, many corners, or curved layouts often need 12–15%.
Screws, tape, and compound
Accessory figures are order-of-magnitude estimates: about 1 screw per square foot of net board, about 0.4 linear feet of tape per square foot, and about 1 gallon of ready-mix joint compound per 100 square feet for a standard multi-coat finish.
They do not replace manufacturer fastening schedules, corner-bead lengths, or Level 5 skim-coat mud volumes. Texture finishes and fire-rated assemblies can change both board type and compound demand.
What this tool does not model
It does not choose ½ in vs ⅝ in Type X, moisture- or mold-resistant boards, double-layer assemblies, sound clips, or code-required fire partitions. Confirm framing spacing, fastener type (wood vs steel studs), and local finish level before ordering.
Interesting facts
4×8 sheets cover 32 square feet each
A standard 4 ft × 8 ft panel is 32 ft². A 4×12 sheet covers 48 ft² and can eliminate horizontal seams on 8 ft walls when hung vertically, at the cost of weight and handling.
Gypsum board is specified under ASTM C1396
In the United States, gypsum wallboard products commonly reference ASTM C1396 for type and thickness. Finish expectations are guided by Gypsum Association GA-214 recommended levels of finish.
½ in is typical for walls; ⅝ in Type X for fire-rated work
Residential walls often use ½ in panels. Many fire-rated assemblies and ceilings call for ⅝ in Type X. Thickness changes weight and rating, not the area math in this calculator.
Butt joints need more finishing than tapered edges
Factory tapered long edges bury tape and mud more cleanly than square butt ends. Planning sheet layout to minimize butts reduces finishing time even when sheet count stays similar.
Waste is mostly cuts, not unbroken leftovers
Offcuts around doors, windows, and out-of-square corners drive waste more than intact leftover panels. Ordering a little extra from the same lot also helps with future patch repairs.
Frequently asked questions
Compute wall area as 2×(length+width)×height, add the ceiling if you are boarding it, subtract doors and windows, add waste, then divide by one sheet’s area and round up. This calculator does that takeoff for you.
4×8 ft (or 1200×2400 mm) is the most common and easiest to move alone. Use 4×9, 4×10, or 4×12 where ceiling height or long walls make fewer seams worth the extra weight.
Plan about 10% for typical rooms with doors and windows. Drop toward 5–8% for simple rectangular walls, and raise to 12–15% for complex layouts, vaults, or many small cuts.
Yes for a tighter sheet count. The room mode deducts standard door and window areas; enter Extra openings for large patio doors or other voids not covered by the counts.
A common planning rule is about one screw per square foot of board (roughly 32 screws on a 4×8 wall sheet). Follow the fastener schedule for your framing spacing and whether you are on wood or steel studs.
Rough guides are about 0.4 linear feet of tape per square foot of board and about one gallon of ready-mix mud per 100 square feet for a standard finish. Level 5 or heavy texture needs more compound.
Yes. Turn Include ceiling on in room mode, or enter the combined wall and ceiling area in area mode. Ceiling hanging often uses closer screw spacing than walls.
No. Thickness affects weight, fire rating, and sag resistance, not coverage area. Pick the product your assembly requires, then order the sheet count from this estimate.
References
- ASTM C1396 / C1396M — Standard Specification for Gypsum Board Industry specification referenced for gypsum wallboard types and thicknesses.
- EN 520 — Gypsum plasterboards: definitions, requirements and test methods European product standard for plasterboard types used across EU markets (often 1200×2400 mm panels).
- GA-214 — Recommended Levels of Finish for Gypsum Board Defines finish Levels 0–5 that drive joint-treatment expectations.
- Sheetrock Brand Gypsum Panels — product data Manufacturer sheet sizes, thicknesses, and installation guidance for common panels.