Drywall Calculator
Work out how many drywall sheets you need for the walls, the ceiling or both. The calculator takes the room size minus doors and windows, adds a waste allowance, divides by the sheet size and rounds up. It also gives a screw count. Partitions, double layers and joint finishing are outside its scope.
Units
Area breakdown
- Walls (minus openings)
- 416.0 sq ft
- Ceiling
- 168.0 sq ft
- Total area
- 584.0 sq ft
- One sheet
- 32.0 sq ft
Before you buy
- This is an area-based estimate, not a sheet-by-sheet layout. Rooms with many corners, soffits or short cuts above doors use more board. Raise the waste allowance in that case (15% is a common figure when there are many openings).
- Longer sheets mean fewer joints to tape. If your walls are 9 ft high or the room is long, 4×9, 4×10 or 4×12 sheets often save both board and finishing time. You'll need help carrying them, though.
- Hanging two layers for fire or sound ratings? Double the sheet count. The screw figure here is for a single layer, and fire-rated assemblies follow their own tested fastener spacing.
- In metric mode, the frame and screw counts follow Russian state estimating norms. They include unavoidable losses and assume hangers about every 50 cm. Knauf's own technical sheets come out lower, for example 0.7 wall hangers per m² instead of 2.14, so treat the metric frame as a generous shopping list.
How this is calculated
Wall area is the room perimeter times the wall height, and ceiling area is length times width, as in Georgia-Pacific's gypsum board guide. Any door and window area you enter is subtracted from the walls only. The calculator adds the waste percentage, divides by the area of one sheet (32 sq ft for a 4×8) and rounds up, because sheets are sold whole. The imperial screw count uses Georgia-Pacific's estimating figure of 1,250 screws per 1,000 sq ft of board. In metric mode, screws and the metal frame use the per-square-metre quantities from Russian state estimating norms GESN 81-02-10-2020: 16.67 screws per m² of wall lining and 22.21 per m² of single-level suspended ceiling, plus channel, track, hangers, connectors and anchors. Those norms already include unavoidable losses, so the waste percentage applies to sheets only. None of this is a structural design.
Common questions
Should I subtract doors and windows?
For the closest estimate, yes. Enter their combined area and it comes off the walls. Many installers don't bother with small openings, because the cut-outs rarely get reused and the waste allowance covers them. Entering 0 just leaves you a bit of spare board.
How much extra drywall should I buy for waste?
10% is the usual starting point for a plain rectangular room, and the calculator uses it by default. Go to 15% if there are many openings, angles or short pieces. Russian state estimating norms work out at about 5% for blank walls and 11–12% for suspended ceilings, so the right figure depends on the layout.
Does it calculate studs or framing?
Not in imperial mode, because the board goes on studs or joists that are usually already there. In metric mode it estimates a metal channel frame (ceiling channel, track, hangers, connectors, anchors) from state estimating norms. Use it as a shopping list, not as a frame design for heavy loads.
Part of Home Improvement Calculators