What it works out
Choose what you know about the wall: its length and height, or its area. You get the number of sheets for each sheet size and the wall size used. Waste is added first, then each total is rounded up once. Doors and windows are not subtracted, so take them off the area yourself.
The formula
- Sheets
- area ÷ sheet area, or length ÷ sheet width, for each sheet size
In words: Sheets = area divided by sheet area, or length divided by sheet width, for each sheet size
Worked example
A wall 12 ft long and 8 ft high, with 4 ft by 8 ft sheets
- Length 12 ft
- Height 8 ft
- Sheet 4 ft × 8 ft (32 ft²)
- Wall area = 12 × 8 = 96 ft²
- Sheets = 96 ÷ 32 = 3
Waste is added first, then each total is rounded up once. Sheets of other sizes are counted side by side.
Good to know
- Doors and windows are not subtracted: take them off the area yourself.
- Joints, corners and trim are not modelled.
- A calculator, not a building-code check: confirm local rules with your building authority.
Questions
Do I subtract windows?
Yes, do it in the area you enter.
Why compare sheet sizes?
A 12 ft sheet can leave fewer seams on a long wall.