Plywood & OSB Sheathing Calculator
Sheets of plywood or OSB for walls, roofs and floors from areas typed one per line, less openings, in your sheet size with waste — plus cost and fasteners.
Gross and net area, exact and rounded-up sheet count with the waste allowance, leftover material, cost at your sheet price and fasteners per sheet and in total from the spacings you enter.
Example: Two 40 × 9 ft walls and a 120 sq ft gable less 60 sq ft of openings is 780 sq ft: 24.4 sheets of 4 × 8, 27 with 10 % waste, 756 at 28 a sheet; 6 in edge / 12 in field nailing is 68 nails a sheet.
Area over sheet area,
rounded up with waste.
How the areas are read, how sheets and fasteners are counted, and what is left to your drawings.
Areas
Each line is a name and either width × height or a plain area; the areas are summed and the openings you enter are subtracted once. Sheets = net area ÷ sheet area × (1 + waste %), rounded up to whole sheets; leftover is the material beyond the net area. Waste covers cuts at corners, angles, damaged sheets and offcuts too small to reuse — 10 % is typical for simple walls, more for hips and gables.
Fasteners
Per sheet: the perimeter divided by the edge spacing, plus the interior supports (framing spacing across the sheet's long side, less the two edges) times the fasteners along each at the field spacing. It assumes the long side runs across the supports; multiply by the sheet count for the total. The spacings are yours — schedules differ by use (wall, roof, shear wall) and are set by your code and drawings.
What this page does not decide
Panel thickness, span rating, orientation, edge blocking, gaps at panel edges and nailing schedules come from your plans or code; nothing here is a design value. Metric sheets are 1.22 × 2.44 m (1 220 × 2 440 mm). Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Sheets = (Σ areas − openings) ÷ (sheet width × length) × (1 + waste) rounded up; fasteners = perimeter ÷ edge spacing + interior supports × (width ÷ field spacing); no code schedule applied
Last reviewed 22 September 2026. How results are checked: How we verify.