Plywood thickness chart
Structural plywood is stamped with a Performance Category, such as 23/32 or 3/4, under the US standard NIST PS 1-22. The category is a name: the standard gives each one a range the panel must measure, a wider range for unsanded panels and a tighter one for sanded panels.
From the standard, NIST PS 1-22
| Category | Unsanded (in) | Unsanded (mm) | Sanded (in) | Sanded (mm) |
|---|---|---|---|---|
| 1/4 | 0.219–0.281 | 5.56–7.14 | 0.234–0.266 | 5.94–6.76 |
| 5/16 | 0.281–0.344 | 7.14–8.74 | 0.297–0.328 | 7.54–8.33 |
| 11/32 | 0.313–0.375 | 7.95–9.53 | 0.328–0.359 | 8.33–9.12 |
| 3/8 | 0.344–0.406 | 8.74–10.31 | 0.359–0.391 | 9.12–9.93 |
| 7/16 | 0.406–0.469 | 10.31–11.91 | 0.422–0.453 | 10.72–11.51 |
| 15/32 | 0.438–0.5 | 11.13–12.7 | 0.453–0.484 | 11.51–12.29 |
| 1/2 | 0.469–0.531 | 11.91–13.49 | 0.484–0.516 | 12.29–13.11 |
| 9/16 | 0.531–0.594 | 13.49–15.09 | 0.547–0.578 | 13.89–14.68 |
| 19/32 | 0.563–0.625 | 14.3–15.88 | 0.578–0.609 | 14.68–15.47 |
| 5/8 | 0.594–0.656 | 15.09–16.66 | 0.609–0.641 | 15.47–16.28 |
| 11/16 | 0.656–0.719 | 16.66–18.26 | 0.672–0.703 | 17.07–17.86 |
| 23/32 | 0.688–0.75 | 17.48–19.05 | 0.703–0.734 | 17.86–18.64 |
| 3/4 | 0.719–0.781 | 18.26–19.84 | 0.734–0.766 | 18.64–19.46 |
| 13/16 | 0.781–0.844 | 19.84–21.44 | 0.788–0.837 | 20.02–21.26 |
| 7/8 | 0.831–0.916 | 21.11–23.27 | 0.849–0.901 | 21.56–22.89 |
| 1 | 0.95–1.05 | 24.13–26.67 | 0.97–1.03 | 24.64–26.16 |
| 1-1/8 | 1.069–1.181 | 27.15–30 | 1.091–1.159 | 27.71–29.44 |
| 1-1/4 | 1.188–1.313 | 30.18–33.35 | 1.213–1.288 | 30.81–32.72 |
Reading the chart
A panel stamped 23/32 that has been sanded must measure between 0.703 and 0.734 inch: it never reaches a full 3/4 inch (0.750). So a dado cut to a full 3/4 inch will be loose on it: measure the sheet you have and cut the dado to it. The standard measures thickness with a micrometer at four points, one near the middle of each edge, and averages them.
The ranges follow a rule. Unsanded panels may be 1/32 inch either side of the category up to 13/16, and 5% either side above it. Sanded panels are held to 1/64 inch up to 3/4, and 3% above it.
Hardwood and Baltic birch plywood
Cabinet-grade hardwood plywood is made to a different standard (ANSI/HPVA HP-1), which is sold rather than published. We have not yet found two makers who publish its actual thicknesses, so this page gives none: measure the sheet. Baltic birch is made in millimetres; see Baltic birch plywood.
Sheet sizes and how far short a panel may run are on plywood sizes; what the letters mean is on plywood grades.