Plywood Calculator
Sheets = area ÷ the panel's area (32 ft² for a 4 × 8), plus a cutting allowance, rounded up — the count is the same for plywood and OSB. A 40 × 30 ft floor is 1,200 ft² ÷ 32 = 37.5 sheets, or 42 with 10% waste. For wall and ceiling board, use the Drywall Sheet Calculator.
How it's calculated: Sheets = area ÷ panel area (32, 36 or 40 ft²), plus the waste allowance, rounded up to whole sheets.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Sheets = Area ÷ sheet area, rounded up, with a cutting allowance
Standard panel = 4 × 8 ft = 32 ft²
Run the calculation to see each step with your own numbers.
A 40 ft × 30 ft floor, 4×8 sheets, 10% waste.
Area = 1,200 ft²
Sheets = 1,200 ÷ 32 = 37.5
+10%, round up = 42 sheets
- Panels are laid with no structural pattern requirement beyond staggered end joints — the waste allowance covers the offcuts.
- For a subfloor, glue and fasteners are separate; for a roof/wall, so is the housewrap/underlayment.
- Large openings (a garage door, a stairwell) should be subtracted from the area first.
- Plywood or OSB — same count?
- Yes. Both come in the same 4×8 ft panel, so the sheet count is identical. The choice is about cost, weight and moisture exposure.
- How much waste should I allow?
- 10% for a simple rectangular floor or wall. A roof with hips, valleys and dormers, or a wall with many openings, produces more unusable offcuts — use 15% or more.
- How many sheets of plywood for 1,000 square feet?
- 31.25 sheets of 4 × 8 ft for the exact area, or 35 with the default 10% cutting allowance. Use 15% or more for a cut-up roof or a wall with many openings.
- Do 4×9 or 4×10 panels change the sheet count?
- Yes — larger panels cover more per sheet. 1,200 ft² takes 30 sheets of 4 × 10 ft (40 ft²) exactly, or 33 with 10% waste, against 42 sheets of 4 × 8 ft.
- Should I subtract openings before counting sheets?
- Subtract large openings, such as a garage door or a stairwell, from the area before counting sheets, then enter the net figure with the known-area option.
Panel size
Standard 4×8 ft panel = 32 ft². Nominal panel size (drywall ASTM C1396, plywood/OSB PS 1 / PS 2).
About the Plywood Calculator
The Plywood Calculator gives the number of 4×8 (or 4×9, 4×10) panels of plywood or OSB for a floor, wall or roof area, with a cutting allowance. Plywood and OSB come in the same panel size, so the count is identical — the choice between them is cost, weight and moisture exposure. Subtract large openings such as a stairwell or garage door from the area first.
What you enter
- Enter
- Length
- Width
- Area to cover
- Panel size
- Waste allowance — Default 10%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Coverage area — the exact result of the calculation.
- Sheets — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Drywall Sheet Calculator — Sheet count only for a given wall or ceiling area and sheet size.
- Roof Area Calculator — Sloped surface area of a simple gable or hip roof from its footprint and pitch.
- Board Foot Calculator — Board feet for a piece or a list of lumber from its dimensions.
- Framing Calculator — Stud count and lineal feet for a wall at a given stud spacing.
Part of the Lumber & Wood calculators.