Plywood Calculator
Sheets = area × (1 + waste) ÷ sheet area, rounded up. A 12 × 14 ft floor is 168 ft²; with 10 % waste, 184.8 ft² ÷ 32 ft² rounds up to 6 sheets of 4 × 8. A layout that does not reuse offcuts can take more: a 10 × 12 ft floor is 5 sheets with 10 %, 6 laid out.
Sheets to buy
6 sheets
184.8 ft² with 10 % waste
- Area
- 168 ft²
- Sheets at the area, no waste
- 5.25
- Layout without reusing offcuts
- 6 sheets
APA leaves a 1/8 in gap at every panel edge and end: the sheets are not laid tight, and the waste allowance covers cuts.
Checked by the Yardstick Math team · How we check
Worked examples
12 × 14 ft floor with 4 × 8 sheets
- Area = 12 × 14 = 168 ft²
- 168 ÷ 32 = 5.25 sheets at the area
- 168 × 1.10 = 184.8 ft² with 10 % waste
- 184.8 ÷ 32 = 5.78, rounded up to 6 sheets
Result: 6 sheets of 4 × 8; the layout also takes 6.
Checked by the automated test “plywood — 12 × 14 ft floor, 10 % waste → 168 ft², 184.8 ft², 6 sheets of 4 × 8 (layout 6)”.
10 × 12 ft floor: area against layout
- Area = 10 × 12 = 120 ft² = 3.75 sheets
- 120 × 1.10 ÷ 32 = 4.13, rounded up to 5 sheets
- Layout: ⌈10 ÷ 4⌉ × ⌈12 ÷ 8⌉ = 3 × 2 = 6 sheets
Result: 5 sheets if offcuts are reused, 6 if they are not.
Checked by the automated test “plywood — 10 × 12 ft: 3.75 sheets at the area, 5 with 10 %, but 6 if offcuts are not reused”.
How it works
Area = length × width (roof: slope length × ridge length × slopes)
Sheets = ⌈area × (1 + waste ÷ 100) ÷ sheet area⌉
Layout, offcuts not reused = min(⌈width ÷ 4⌉ × ⌈length ÷ 8⌉, ⌈width ÷ 8⌉ × ⌈length ÷ 4⌉)
Assumptions
- A 4 × 8 sheet is 32 ft²: APA gives the “nominal 48 inches by 96 inches”; panels are made slightly smaller so they can be spaced.
- APA recommends a “1/8-inch space between panel edge and end joints”: sheets are not laid tight, and the waste covers cuts.
- The main figure reuses offcuts (area + waste); the layout line shows the whole sheets a grid takes when they are not reused.
- Roofs are measured along the slope: no pitch is computed here, use the roof pitch calculator for that.
Reference table
| Area | No waste | 10 % waste | 15 % waste |
|---|---|---|---|
| 100 ft² | 4 | 4 | 4 |
| 200 ft² | 7 | 7 | 8 |
| 320 ft² | 10 | 11 | 12 |
| 500 ft² | 16 | 18 | 18 |
| 768 ft² | 24 | 27 | 28 |
Rounded up to whole sheets of 32 ft²; offcuts reused.
Before you buy
- One line per surface. Add each floor, wall or roof slope as its own area; the layout line counts whole sheets for each.
- Sheet size. If your supplier stocks 4 × 9 or 4 × 10 sheets, pick them in the selector: a 9 or 10 ft wall then has no horizontal joint.
- Thickness and grade. This count does not choose the panel: span rating and thickness come from the panel stamp and your code.
Common mistakes
- Laying sheets tight APA recommends a 1/8-inch space between panel edge and end joints: panels that cannot expand may buckle.
- Counting the area without waste 168 ft² is 5.25 sheets, but 6 are needed with 10 % for cuts: buying 5 leaves the floor short.
- Dividing by 32 for a 4 × 10 sheet A 4 × 10 sheet holds 40 ft²: 480 ft² is 15 sheets of 4 × 8 but 12 of 4 × 10, before waste.
- Measuring a roof on the ground Roof sheathing covers the slope, not the footprint: measure from eave to ridge along the roof.
Frequently asked questions
How big is a sheet of plywood?
The standard sheet is 4 × 8 ft, 32 ft²: APA calls it the nominal 48 inches by 96 inches, made slightly smaller so panels can be spaced. The calculator also takes 4 × 9 (36 ft²) and 4 × 10 (40 ft²) sheets.
How many sheets of plywood do I need?
Multiply the area by 1.10 for waste and divide by 32 ft² per 4 × 8 sheet, then round up: a 12 × 14 ft floor (168 ft²) takes 6 sheets.
How many sheets of plywood for a roof?
Measure each slope from eave to ridge and multiply by the ridge length: two 12 × 30 ft slopes are 720 ft², 25 sheets of 4 × 8 with 10 % waste.
Sources
Formula, examples and sources checked on by the Yardstick Math team. How we check our formulas.
- Plywood — APA – The Engineered Wood Association, accessed
- Builder Tips: Prevent Buckling with Proper Spacing — APA – The Engineered Wood Association, accessed