# Plywood Calculator

> Add each area to cover and subtract openings. Pick the sheet size, waste percent and price per sheet. You get the sheets to buy, the leftover area and the cost. A 24 × 30 ft roof deck on 4 × 8 sheets with 10% waste needs 25 sheets.

Canonical: https://receiptscanner.co/tools/plywood-calculator
Updated: 2026-10-28 · Sources re-checked by: 2027-10-28

This is a free interactive calculator that runs in the browser. Nothing you type is stored or sent. Results are estimates.

## How it works

Area = the sum of each rectangle (length × width), minus the areas you take off for openings. Sheet area = the sheet's width × length, so a 4 × 8 ft sheet is 32 sq ft. Sheets = area ÷ sheet area × (1 + waste), rounded up. Leftover = sheets × sheet area − area. Cost = sheets × the price per sheet. Plywood is sold by a nominal thickness, but performance-rated panels are often slightly thinner, for example a 1/2 in panel is commonly 15/32 in, so check the stamp.

**Sheets for common areas on 4 × 8 ft sheets (10% waste)**

| Area | Sheets |
| --- | --- |
| 100 sq ft | 4 |
| 200 sq ft | 7 |
| 400 sq ft | 14 |
| 800 sq ft | 28 |
| 1,600 sq ft | 55 |

**Sheet sizes and what each covers**

| Sheet | Area | Sheets for 720 sq ft, no waste |
| --- | --- | --- |
| 4 × 8 ft | 32 sq ft | 23 |
| 4 × 10 ft | 40 sq ft | 18 |
| 4 × 12 ft | 48 sq ft | 15 |
| 5 × 5 ft | 25 sq ft | 29 |

**Nominal and typical actual thickness of performance-rated panels**

| Nominal | Often actual | Common uses |
| --- | --- | --- |
| 1/4 in | 7/32 in | Underlayment, crafts, backs |
| 3/8 in | 11/32 in | Light sheathing, soffits |
| 1/2 in | 15/32 in | Wall and roof sheathing |
| 5/8 in | 19/32 in | Roof sheathing, subfloor |
| 3/4 in | 23/32 in | Subfloor, shelving |

## Worked example: a 24 × 30 ft roof deck on 4 × 8 ft sheets

1. Area: 24 × 30 = 720 sq ft. A 4 × 8 ft sheet is 32 sq ft.
2. Sheets: 720 ÷ 32 = 22.5. With 10% waste: 22.5 × 1.10 = 24.75, so 25 sheets.
3. Leftover: 25 × 32 − 720 = 80 sq ft.
4. At $40 a sheet the cost is 25 × 40 = $1,000.00.

## FAQ

### How many sheets of plywood do I need?
Divide the area by the area of one sheet (32 sq ft for a 4 × 8) and add about 10% for cuts. Round up to whole sheets.

### How much waste should I allow for plywood?
About 10% for a simple rectangle and more for roofs with hips, many openings or short runs. The box starts at 10%, and you can change it.

### What thickness should I use?
It depends on the job, the joist or rafter spacing and your local code. The span rating stamped on the panel tells you how far it can span. Ask your building department or supplier.

### Why is a 1/2 inch sheet not exactly 1/2 inch?
Performance-rated panels are made to a strength standard, not an exact thickness, so a nominal 1/2 in sheet is often 15/32 in. The stamp on the panel states the real rating.

### Should I subtract windows and doors?
For wall sheathing, take off large openings, but keep some waste because the cut-outs rarely make usable pieces. Use the subtract tick on each opening.

### Does the sheet size matter?
Yes. Longer sheets mean fewer seams but are harder to carry and cut. Pick the size you can handle, and see how the count changes in the table.

## Sources

- [Plywood: how panels are made, grades and common sheet sizes](https://en.wikipedia.org/wiki/Plywood) (checked 2026-10-28)
- [APA - The Engineered Wood Association: performance-rated panels and their span ratings](https://www.apawood.org/) (checked 2026-10-28)

This calculator is an estimate for planning. Panel grade, thickness and fastening depend on the job and local code, so confirm them with your building department or supplier before you buy.