Plywood Sizes and Thicknesses (Nominal vs Actual)

Plywood sizes name a category, and the thickness a panel is called is not the thickness it measures. In the US plywood standard PS 1, a panel of the 1/2 Performance Category may measure from 0.469 in^[1] to 0.531 in^[1] when it is unsanded or touch-sanded, and from 0.484 in^[1] to 0.516 in^[1] when it is sanded.

Estimates for planning, not professional advice. Read the full notice.

Work it out for your own sizes

Count the sheets for my floor

Example to try: Floor length 12 ft, Floor width 16 ft

Plywood thickness by Performance Category

The least and greatest thickness PS 1 allows for six Performance Categories, for unsanded and touch-sanded panels and for sanded panels

The least and greatest thickness PS 1 allows for six Performance Categories, for unsanded and touch-sanded panels and for sanded panels
Performance Category	Unsanded or touch-sanded, least	Unsanded or touch-sanded, greatest	Sanded, least	Sanded, greatest
1/4 Performance Category	0.219 in	0.281 in	0.234 in	0.266 in
3/8 Performance Category	0.344 in	0.406 in	0.359 in	0.391 in
1/2 Performance Category	0.469 in	0.531 in	0.484 in	0.516 in
5/8 Performance Category	0.594 in	0.656 in	0.609 in	0.641 in
3/4 Performance Category	0.719 in	0.781 in	0.734 in	0.766 in
1 Performance Category	0.95 in	1.05 in	0.97 in	1.03 in

Source: ^[1]

Each row is one row of the standard's plywood thickness table, with thicknesses in inches as the standard prints them beside its metric figures. The standard bases panel measurements on a moisture content of nine percent.

Length and width

PS 1 allows a panel's length and width a tolerance of plus 0 in^[1] and minus 0.0625 in^[1] on the size the manufacturer states, so a panel is never longer or wider than its stated size.

A tolerance of plus zero (0) mm, minus 1.6 mm (1/16 in) shall be allowed on the manufacturer's stated length and/or width.

National Institute of Standards and Technology (U.S. Department of Commerce), Voluntary Product Standard PS 1-19, Structural Plywood (PS 1-19, December 2019)^[1]

To count sheets for a floor or a wall from the sheet size you buy, use the plywood calculator. It takes the sheet size from your supplier, not from this page.

Questions

Is half-inch plywood really half an inch thick?

Not exactly. PS 1 names a panel by its Performance Category and allows a range of measured thickness for each. The table gives the range for the 1/2 category and five others.

Why does sanded plywood have a narrower range?

In the table the sanded columns are closer together than the unsanded and touch-sanded columns for every category, because the standard holds sanded panels to a smaller thickness tolerance.

Does this page give the size of a sheet of plywood?

No. It gives the thickness ranges and the length and width tolerance from PS 1. Your supplier states the sheet size you are buying, and the plywood calculator takes it from you.

Calculate it for your project

Enter your own sizes to get the amount to buy or the layout figures, with the working shown and a page to print.

Open the plywood calculator

Sources (1)

Voluntary Product Standard PS 1-19, Structural Plywood (opens in new tab), National Institute of Standards and Technology (U.S. Department of Commerce), PS 1-19, December 2019. Code or government.
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 1/2 PERF CAT 11.91 (0.469) 13.49 (0.531) 12.30 (0.484) 13.10 (0.516)”

“A tolerance of plus zero (0) mm, minus 1.6 mm (1/16 in) shall be allowed on the manufacturer's stated length and/or width.”
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 1/4 PERF CAT 5.56 (0.219) 7.14 (0.281) 5.95 (0.234) 6.75 (0.266)”
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 3/8 PERF CAT 8.73 (0.344) 10.32 (0.406) 9.13 (0.359) 9.92 (0.391)”
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 5/8 PERF CAT 15.08 (0.594) 16.67 (0.656) 15.48 (0.609) 16.27 (0.641)”
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 3/4 PERF CAT 18.26 (0.719) 19.84 (0.781) 18.65 (0.734) 19.45 (0.766)”
“TABLE 10. PLYWOOD THICKNESS REQUIREMENTS … 1 PERF CAT 24.13 (0.950) 26.67 (1.050) 24.64 (0.970) 26.16 (1.030)”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1)

These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.

Estimates for planning, not professional advice. This page is provided as is. Its figures are estimates worked out from what you enter and from published product data. It is not engineering, architectural, building-code, legal or contractor advice. Products and local codes vary, so check product labels, your supplier and your local building department. For structural work, consult a licensed professional.

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Made with HoneyDoMath.com. Estimates for planning; check product labels and local codes before you buy or build.