Plywood Sheet Calculator
Calculate how many sheets of plywood or OSB you need to cover an area, with a waste allowance.
How it works
sheets = ceil(area × 1.10 ÷ sheet size)
Divide the total area by the square footage of one sheet — a 4 × 8 sheet is 32 sq ft — and round up, adding about 10% for cuts and waste. Real layouts rarely fall on clean 4-foot lines, so the waste allowance covers the offcuts and the staggered seams that a proper subfloor or sheathing job requires.
Worked example
640 sq ft of subfloor in 4 × 8 sheets: 640 × 1.10 = 704 ÷ 32 = 22 sheets. Without waste it would be exactly 20, but almost no room tiles out perfectly on the grid.
Frequently asked questions
How many square feet is a sheet of plywood?
A standard 4 × 8 sheet is 32 square feet. Half sheets (4 × 4) are 16 and quarter sheets (2 × 4) are 8 — handy for small patches without buying full sheets.
Should I gap plywood sheets?
Yes — leave about 1/8 in between sheets for subfloor and sheathing so they can swell with humidity without buckling. Many tongue-and-groove subfloor panels are designed to self-gap.
Plywood or OSB?
OSB is cheaper and fine for most sheathing and subfloor; plywood is lighter, holds screws better and tolerates getting wet and drying out. Both come in the same sheet sizes, so the count here is identical.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.