Plywood Calculator
Estimate how much plywood you need by area and depth — plus bags and total cost. Switch between imperial and metric units.
Plywood Calculator
Estimate how much you need — and the cost.
- sq meters 10.22
Quick coverage reference
A 4×8 ft sheet of plywood or OSB covers 32 sq ft. Sheets = round up (area × (1 + waste) ÷ 32).
How it's calculated
- Add about 10% for cuts and offcuts; more for roofs and walls with many openings or angled edges.
Source: inchcalculator.com/plywood-calculator/ (4×8 = 32 sq ft cross-checked)
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</script>How many sheets of plywood do I need?
Plywood and OSB are sold by the sheet, and the standard sheet is 4 × 8 ft = 32 sq ft. Whether you're decking a roof, sheathing walls, or laying a subfloor, the estimate is the area you're covering plus a waste allowance, divided by 32.
Use sheets = area (sq ft) × (1 + waste%) ÷ 32, rounded up. A 320 sq ft subfloor at 10% waste comes to 11 sheets. Add 10% for the offcuts left when sheets meet walls and openings — roofs and walls with lots of cuts run higher.
How to measure for plywood
Measure the area
Length × width of the floor, wall, or roof plane you are sheathing. Total multiple planes separately.
Add a waste factor
10% covers normal cuts and offcuts. Cut-up roofs, gables, and stair openings can push it to 15%.
Confirm the sheet size
Standard sheets are 4 × 8 ft (32 sq ft). The calculator uses 32 by default — change it if you buy a different size.
Read sheets needed
The result rounds up to whole sheets, since you can only buy full panels.
Plywood buying tips
Subfloors typically use 3/4 in tongue-and-groove; wall sheathing 1/2 in; roof decking 1/2–5/8 in depending on rafter spacing.
OSB is cheaper and common for sheathing and subfloor; plywood is lighter and handles moisture cycles a little better. Both come 4 × 8.
Stagger seams and run sheets perpendicular to joists or rafters for strength — sketch the layout so you order the right count.
Plywood calculator FAQ
How many square feet is a sheet of plywood?
A standard 4 × 8 ft sheet of plywood or OSB covers 32 square feet.
How do I calculate how much plywood I need?
Divide the area you are covering by 32 sq ft per sheet, after adding about 10% for waste, then round up to whole sheets.
How many sheets of plywood for 1000 square feet?
About 32 sheets at 32 sq ft each, or roughly 35 sheets once you add 10% for cuts and waste.
What thickness of plywood should I use?
3/4 in for subfloors, 1/2 in for wall sheathing, and 1/2–5/8 in for roof decking depending on framing spacing.
Is OSB the same size as plywood?
Yes — both come in standard 4 × 8 ft sheets, so the sheet count is the same. OSB is usually cheaper for sheathing and subfloor.