Drywall, gypsum board & plasterboard planning
Drywall Calculator
Estimate boardable wall, ceiling or known surface area, apply one visible waste allowance, and plan whole boards from the physical panel size you intend to use.
Estimate drywall needed
Measure boardable area → add explicit waste → plan whole boards by physical panel size.
Measure surface area before you buy boards
How the Drywall Calculator works
ProjectFigures estimates ordinary interior drywall, gypsum board or plasterboard from the boardable surface you measure, applies one visible extra/waste allowance, then converts the adjusted area into an area-based whole-board planning estimate using the physical panel size you select.
How much drywall do I need?
Measure the walls or surfaces that will receive board. In Room mode, wall area comes from room perimeter multiplied by wall height. You can optionally deduct measured openings and include the ceiling. Custom Surfaces mode handles individually measured rectangles, while Known Net Area accepts an area you have already measured and adjusted for openings.
Drywall, gypsum board, wallboard and plasterboard
These terms vary by market. Drywall, gypsum board and wallboard are common North American terms, while plasterboard is common in the UK and Australia. Sheetrock® is a USG brand name, not the universal technical name for every gypsum board product.
Room wall-area formula
For a rectangular room, ProjectFigures uses2 × (length + width) × wall height. Repeated identical rooms multiply the per-room result by the room quantity. The calculator keeps these wall results distinct from any included ceiling area.
Ceilings
Ceiling drywall is optional in Room mode. When enabled, ceiling area islength × width for each identical room. If the ceiling requires a different board product, thickness, layer count or specification, calculate it separately rather than mixing incompatible product assumptions.
Doors, windows and other openings
Drywall estimating practices differ on whether openings should be deducted. V1 therefore defaults to no deduction and never inserts universal door or window sizes. If you deliberately want to subtract openings, choose the measured-opening option and enter the combined area per identical room or surface.
Custom surfaces and known area
Use Custom Surfaces for individually measured wall or ceiling rectangles. Use Known Net Area when you already know the boardable square footage or square metres before waste. Direct area is already net, so ProjectFigures does not apply another opening deduction.
Common board sizes
Board dimensions vary by country, manufacturer and product. ProjectFigures offers common planning shortcuts such as 4 × 8 ft, 4 × 10 ft and 4 × 12 ft, plus metric options such as 1200 × 2400 mm, 1200 × 2700 mm and 1200 × 3000 mm. Always check the actual panel you plan to purchase.
Board size vs board count
The calculator first determines mathematical adjusted boardable area. It then divides that unrounded area by the selected board face area and rounds to a whole-board planning count. Changing display units converts the same physical board; it never silently replaces a 4 × 8 ft panel with a different metric panel.
Extra material and waste
Cuts, damage, room complexity, board orientation and installation details can change actual material use. ProjectFigures starts at an editable 10% extra allowance, but 10% is a planning starting point rather than a universal construction rule. Set it to the value appropriate for your actual project and product guidance.
Why the board count is not a layout optimizer
Area divided by panel area cannot optimize horizontal versus vertical hanging, framing alignment, seams, joint staggering, long-board selection, doorway cut reuse or offcuts. ProjectFigures therefore labels the result as an area-based whole-board planning estimate.
Board thickness and specialty products
Thickness, moisture resistance, fire-rated assemblies, acoustic systems and other specialty requirements can matter for product selection and code compliance, but they do not belong in a simple face-area quantity formula. V1 does not recommend a board type, thickness or tested assembly.
Joint compound, tape and fasteners
Joint compound, tape, screws, nails, corner bead and adhesive are outside V1. Their quantities can depend on installation method, framing, spacing, number of layers, jointing system and product instructions, so ProjectFigures does not fabricate universal accessory rates.
Square feet and square metres
US customary mode supports feet, inches and square feet. Metric mode supports metres, centimetres and square metres. Valid physical inputs keep a last-valid canonical value, so repeated unit switching does not accumulate rounding drift or change calculation semantics.
Worked US example
A 12 ft × 10 ft room with 8 ft walls has 352 ft² of wall area before openings. With no opening deduction and 10% extra, the adjusted area is 387.2 ft². Using a 4 × 8 ft board with 32 ft² of face area, the area-based whole-board estimate is 13 sheets.
Worked metric example
A 4 m × 3 m room with 2.4 m walls has 33.6 m² of wall area. With 10% extra, the adjusted area is 36.96 m². A 1.2 m × 2.4 m board has 2.88 m² of face area, producing an area-based estimate of 13 boards.
Common drywall-estimating mistakes
- Using one global board size without checking the actual product available.
- Subtracting openings automatically even when the installation still needs surrounding sheets and cuts.
- Applying a waste percentage twice.
- Treating area-based sheet count as a seam or cut-layout optimizer.
- Changing unit systems and accidentally substituting a different physical panel size.
- Assuming thickness, fire rating or moisture suitability can be inferred from square area.
Frequently asked questions
How do I calculate drywall for a room?
Measure length, width and wall height. ProjectFigures calculates perimeter × height, then applies any measured opening deduction, optional ceiling and explicit waste allowance.
Should I subtract doors and windows?
There is no universal V1 rule. ProjectFigures defaults to no deduction and lets you subtract measured opening area when that matches your planning method.
Is 10% waste always required?
No. It is only the ProjectFigures starting value. Adjust it using your actual project, installer or product guidance.
Does the sheet count optimize cuts?
No. It is an area-based whole-board planning estimate and does not optimize orientation, seams, framing alignment or offcuts.
Can I use custom board dimensions?
Yes. Choose Custom and enter the physical width and length of the board you plan to buy.
Does this estimate drywall screws, tape or mud?
No. Those accessory quantities are outside Drywall V1 because product and installation conditions can materially change them.
Does this recommend fire-rated or moisture-resistant board?
No. Product selection, thickness, code, fire, moisture and acoustic requirements are outside this quantity calculator.
Does it work in square metres?
Yes. Metric mode uses metres, centimetres and square metres while preserving the same canonical project geometry.
Related tool
Planning the wider contractor job after estimating board quantity? Continue to theContractor Job Pricing Calculator and use your own supplier drywall cost in the broader pricing workflow.
Area-based drywall/plasterboard quantity planning only. Board layout, thickness, product suitability, code requirements and accessory quantities require separate project guidance.