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1/2 plywood actual thickness

1/2" plywood can carry either of two PS 1 stamps, 15/32 or 1/2, and they're 1/32" apart.

Sanded 15/32 is held to 0.453" to 0.484".

Start from

Surface

Size name

Called 1/2"

Stamped 15/32

.451" (11.5 mm) on the label, and 0.438" to 0.500" unsanded.

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15/32" plywood router bit Digital caliper

A panel stamped 1/2 instead is labeled .483" (12.3 mm), 0.469" to 0.531" unsanded.

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15/32 or 1/2 on the stamp

Boise Cascade’s plywood sheathing guide lists both a 15/32" and a 1/2" panel. Georgia-Pacific makes its Plytanium rated sheathing in 15/32, as 3-ply and 4-ply panels, both labeled 0.451". Weyerhaeuser’s southern pine plywood list has 15/32 4-ply rated sheathing and 15/32 4-ply CDX. Unsanded, the two categories share 0.469" to 0.500", so a sheet measuring in that band could be either, and the fraction on its stamp says which. APA’s sample Rated Sheathing stamp reads THICKNESS 0.451 IN. and 15/32 CATEGORY.

Sanded 15/32 and 1/2

Sanded panels get a tighter tolerance, 1/64" either side of the category, so sanded 15/32 runs 0.453" to 0.484" and sanded 1/2 runs 0.484" to 0.516". The two meet at 0.484". PS 1’s recommended labels, from its nonmandatory Appendix D, are .453" and .484" for sanded panels, and .451" and .483" for unsanded ones.

Hardwood panels

Decorative hardwood plywood, the kind made for cabinet and furniture panels, follows the HP-1 standard instead of PS 1, so neither range above applies to it. Convert a caliper reading from the sheet itself.

Building with 1/2 plywood

  • Pocket holes: measure the sheet, then pick that thickness in the pocket-hole screw selector.
  • Screw length: measure the sheet first, then size the screw with how long a screw should be.
  • Pilot holes: the pilot hole finder sizes plywood from its softwood column.
  • Sheathing: for a floor, roof or wall, a rated panel’s span rating and your local building code set which panel goes there, so check with your building department.

Common questions

Is 15/32 plywood the same as 1/2 plywood?

No. They're separate PS 1 categories, and 15/32 is 1/32 inch thinner, with a recommended label of .451 inch against .483 inch.

What is 15/32 plywood in mm?

15/32 inch is 11.9 mm. A 15/32 panel's .451 inch label comes to 11.5 mm, and unsanded it can run from 11.1 to 12.7 mm.

Keep going

Plywood thickness chartevery category, PDFPlywood thickness converterany size or reading3/4 plywood actual thickness23/32, .703"Pocket-hole screw selectorby stock thicknessLumber sizesboards are smaller too

Where we get our information from

The 15/32 and 1/2 ranges and labels come from PS 1-22 (Table 10 and Appendix D), and the maker lines from Boise Cascade’s, Georgia-Pacific’s and Weyerhaeuser’s own spec sheets and product pages. APA’s TT-054C gives the sample stamp. Millimetres are worked out from the inch figures. Checked against published data from NIST, APA, Boise Cascade, Georgia-Pacific and Weyerhaeuser (plus 1 more).

See all 6 sources
  • NIST, Voluntary Product Standard PS 1-22, Structural Plywood (2023)
  • APA, Panel Thickness Tolerances and Labeling, Technical Topics TT-054C (2013): Table 1 and sample panel trademarks
  • Boise Cascade, Plywood Sheathing Specifications Guide (LMB-6400)
  • Georgia-Pacific, Plytanium Plywood Rated Sheathing (product page and specification sheet)
  • Weyerhaeuser, Southern Yellow Pine Plywood (product page)
  • USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-190, 2010), chapter 11, wood-based composite materials

These ranges cover US structural plywood made to PS 1, and a sheet made to another standard can measure outside them.