Plywood Calculator
Enter the surface dimensions to see how many sheets of plywood, OSB or other panel goods you need for subfloor, sheathing or roof decking.
Result
- Sheets before waste
- 12 sheets
- Area to cover
- 384 sq ft
- Area with waste
- 422.4 sq ft
Formula
- Area = length × width
- Sheets = area × (1 + waste) ÷ sheet area, rounded up
- A 4 × 8 ft sheet covers 32 sq ft
How the Plywood Calculator works
Panel goods are sold in full sheets, so the count is the covered area divided by the area of one sheet, rounded up. Waste covers cuts around edges, openings and staggered joints.
For roof decking, use the sloped roof area and not the building footprint. The roofing calculator converts footprint and pitch to roof area.
Worked example
A 24 ft × 16 ft floor is 384 sq ft. That is exactly 12 sheets of 4 × 8. With 10 percent waste the area is 422.4 sq ft, so buy 14 sheets.
Frequently asked questions
How many square feet does a sheet of plywood cover?
A standard 4 × 8 foot sheet covers 32 square feet. A 4 × 10 covers 40 and a 4 × 12 covers 48.
How much waste should I allow for plywood?
Allow 5 to 10 percent for simple rectangles and up to 15 percent for roofs with hips and valleys.
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