3/4 plywood actual thickness
3/4" plywood sheathing is stamped 23/32 and labeled .703" (17.9 mm), and it can measure 0.688" to 0.750".
Sanded 23/32 is held tighter, 0.703" to 0.734".
Start from
Surface
Size name
Inches or mm, such as 0.70, 17.8 mm or 23/32.
Called 3/4"
Stamped 23/32
.703" (17.9 mm) on the label, and 0.688" to 0.750" unsanded.
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A panel stamped 3/4 instead is labeled .734" (18.6 mm), 0.719" to 0.781" unsanded.
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Reading the stamp
Under PS 1, every panel’s mark shows its bond classification (Exterior or Exposure 1), its grade or a certification agency’s mark, the symbol PS 1-22, the Performance Category, and the thickness in thousandths of an inch. The category can be written out or shortened to PERF CAT, CAT or Category. On a sheet called 3/4, look for 23/32 CAT beside .703, or 3/4 CAT beside .734. APA’s sample Rated Sturd-I-Floor stamp reads THICKNESS 0.703 IN. and 23/32 CATEGORY.
Why stamps carry a category and a decimal
PS 1 created Performance Categories after complaints that plywood thickness labels didn’t comply with NIST Handbooks 130 and 133, the US packaging and labeling rules. Earlier editions of PS 1 let a panel run 1/32" under its nominal thickness, and the NIST rules for structural panels don’t allow that. The categories follow the thickness names used in the US building codes, and the same revision made a decimal thickness label mandatory. At 3/4, Weyerhaeuser’s southern pine plywood list has 23/32 rated sheathing, 23/32 CDX and 23/32 CCX. Georgia-Pacific lists its Plytanium 23/32 sheathing at 0.703", matching PS 1’s label, and Roseburg’s AC sanded panel is 23/32" thick, 5 ply.
Cabinet plywood is different
Hardwood plywood for cabinets and furniture is made to HP-1, which grades panels by face veneer, bond and core, so the PS 1 ranges don’t apply to it. Measure it and convert the reading.
Building with 3/4 plywood
- Pocket holes: the pocket-hole screw selector gives the screw for your stock thickness.
- Screw length: work from the sheet’s real thickness with the rule in how long a screw should be.
- Pilot holes: plywood takes the softwood pilot, and the pilot hole finder opens on plywood.
- Floors, roofs and walls: rated panels carry a span rating, and that rating and your building code decide which panel to use. Ask your building department.
- Lumber: boards have the same gap between name and size, and a 2x4 is 1-1/2" x 3-1/2" (lumber sizes).
Common questions
What is 23/32 plywood in mm?
23/32 inch works out to 18.3 mm. The panel's label, .703 inch, is 17.9 mm, and unsanded it can measure 17.5 to 19.1 mm.
Can 3/4 plywood measure more than 3/4 inch?
Yes. A panel in the 3/4 category can measure up to 0.781 inch unsanded or 0.766 inch sanded. The 23/32 category stops at 0.750 inch unsanded.
Where we get our information from
The 23/32 and 3/4 figures are PS 1-22’s (Table 10 and Appendix D), and the maker lines come from Weyerhaeuser’s, Georgia-Pacific’s and Roseburg’s own pages. The sample stamp and the NIST labeling reason are from APA’s TT-054C. Millimetres are converted from inches, rounded to 0.1 mm. Checked against published data from NIST, APA, Weyerhaeuser, Georgia-Pacific and Roseburg (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
- Weyerhaeuser, Southern Yellow Pine Plywood (product page)
- Georgia-Pacific, Plytanium Plywood Rated Sheathing (product page and specification sheet)
- Roseburg, Exterior Core sanded plywood (product page)
- USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-190, 2010), chapter 11, wood-based composite materials
Figures are for US structural plywood made to PS 1. Other plywood can measure differently, so measure the sheet when the thickness matters.