3/8 Plywood: Thickness, Sizes, Uses & Strength Guide
Complete guide to 3/8 plywood: actual thickness (11/32 inch), CDX and hardwood grades, uses for walls, roofing, and cabinetry, strength ratings, pricing, and how it compares to other plywood thicknesses.
Ask a yard for 3/8 plywood and you will get a panel that is usually 11/32 inch thick under APA PS 1 practice — about 8.7 mm — not a full three-eighths on the caliper. That gap is normal. It wrecks dado fits when someone routes a true 0.375 groove. CDX is the everyday buy for covered wall sheathing at 16-inch studs, light roof decks in gentle load zones, underlayment patches, cabinet backs, and craft blanks. It is not a structural subfloor, not a heavy shelf, and not a concrete form. Step to 1/2 or 3/4 for those.
Code cares about the nominal rating and the span stamp. Cabinetmakers care about the micrometer. Both are right for their job.
Where it sits in the thickness ladder
Above 1/4-inch backs, below the 1/2-inch sheets most new-build sheathing specs prefer. Some IRC paths still allow 3/8 CDX at 16-inch studs. Plenty of AHJs already want 7/16 OSB or 1/2 plywood for wind margin. Read the local book before the truck leaves.
| Callout | Number |
|---|---|
| Nominal | 3/8 in |
| Typical APA actual | 11/32 in (0.344) |
| Metric approx. | ~8.7 mm |
Sizes and grades
Stock sheet is 4×8. Half sheets show up at retail. Metric programmes often use 9 mm in 1220×2440 or 1250×2500. CDX moves volume: C face, D back, exposure glue for construction wetting that will be covered. BCX and ACX clean up the face for paint. Sanded hardwood 3/8 — birch, oak, maple — covers doors and drawer bottoms. The wider grade map is in the grades guide.
Jobs it handles — and jobs it does not
Wall sheathing when code allows. Roof decks only in light-cover, low-snow, tight-rafter cases; most roofs want 1/2 or 5/8. Underlayment over a sound subfloor. Cabinet backs and scroll-saw work. Hard no on structural subfloor, heavy shelves, and concrete forming — pour pressure moves thin sheets.
Uniform load talk around 30–40 psf at a 16-inch span shows up for softwood CDX planning. A 24/0-style stamp is a roof span story, not a floor panel. Point loads are the failure mode. Deeper numbers live in the weight capacity guide.
Versus thicker neighbors
Pick 3/8 over 1/4 when you need more stiffness than a thin back. Pick 1/2 when roofs, point loads, or modern sheathing specs show up. Pick 5/8 or 3/4 for subfloors, forms, and shelves. Three-eighths often costs less per sheet than 1/2 in the same grade when you are covering large covered walls that code still allows. Retail CDX in many 2026 US markets sits roughly in the high teens to high twenties USD per 4×8 — planning bands only, not a mill quote.
Actual thickness? Usually 11/32. Roofing? Limited cases only. Shelves? Light and short maybe; bookshelves want 3/4. 3/8 vs 11/32? Same panel. Forms? No — see the form plywood guide.
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