Drywall Calculator
Estimate board quantity for a rectangular room, including an optional ceiling. Supports editable sheet sizes, opening deductions and multiple layers. Use one consistent measurement system.
Calculate drywall sheets for a room
Enter the length, width and wall height of one rectangular room. Select whether to include the ceiling, then enter the combined area of openings you plan to subtract. Sheet width and length use the same unit as the room. In metric mode, a 1.2 × 2.4 metre panel must be entered as 1.2 and 2.4.
Wall area = 2 × (length + width) × height. Ceiling area = length × width when included. Subtract wall openings, multiply by the number of layers, add the cutting allowance, then divide by one sheet's area and round up. This is an area estimate, not a board layout or cutting plan.
Worked example
A 12 × 10 foot room with 8-foot walls has 352 square feet of wall area. Include a 120-square-foot ceiling and deduct a 21-square-foot door: the net coverage is 451 square feet. One layer with 10% allowance needs 496.1 square feet. With 4 × 8 foot sheets, round 15.503 sheets up to 16. At 15 per sheet, the board cost is 240.
Should I subtract doors and windows?
Subtract only the opening area you expect to save in your board layout. Small openings may still need full sheets cut around them. Leaving these openings undeducted can be a useful conservative estimate. Openings cannot exceed the total wall area in this calculator.
Does this estimate drywall mud, screws or tape?
No. Joint compound, tape and fastener requirements depend on the installation and finishing system. Use manufacturer guidance for the selected boards and finishing products. Board area alone cannot specify screw spacing, framing support, fire resistance or the number of finishing coats.
Can I estimate plasterboard in metric units?
Yes. Select metres, enter all lengths in metres and opening area in square metres. Switching the unit selector does not convert existing numbers. Sheet dimensions are editable for locally available plasterboard sizes.
How much waste should I allow?
The example uses 10%, but the appropriate allowance depends on room geometry, sheet orientation, cuts and offcut reuse. For several rooms, calculate each separately and review whether offcuts can be shared. The estimate excludes framing, finishing materials, delivery, tax and labour.
Reference: USG wallboard estimator and installation assumptions.
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Reviewed 4 November 2026. Free, no signup. Calculations run locally in your browser. Results are estimates; confirm product specifications before ordering.
Planning the finishing materials? Use our drywall mud and tape calculator. Before closing the walls, estimate packs or bags with the insulation quantity calculator.