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Woodworking Math

5/8 plywood: actual thickness and weight

Sanded panel measures

0.609–0.641 in

15.47–16.28 mm

From the standard, NIST PS 1-22

A 4 × 8 ft sheet weighs about

60.8 lb

1.9 lb per square foot

One source: APA – The Engineered Wood Association, the trade association that publishes the panel design specification

How thick 5/8 plywood really is

5/8 is a Performance Category, the name stamped on the panel under the US plywood standard, NIST PS 1-22. The standard does not hold the panel to exactly 5/8 in; it gives a range. Sanded panels, the smooth faces sold for cabinets and furniture, are held to a tighter range than unsanded sheathing.

PanelInchesMillimetres
Sanded0.609–0.64115.47–16.28
Unsanded, touch-sanded or overlaid0.594–0.65615.09–16.66

Cutting a dado or rabbet for it? Measure the sheet you have: any panel inside the range meets the standard. Every category side by side is on the plywood thickness chart.

What a sheet of 5/8 plywood weighs

APA gives 1.9 lb per square foot as the approximate weight of 5/8 plywood for working out dead loads, and says to add 10% for OSB. A sheet is that weight times its area.

PieceAreaAbout
Full sheet, 4 × 8 ft32 sq ft60.8 lb
Half sheet, 4 × 4 ft16 sq ft30.4 lb
Quarter sheet, 2 × 4 ft8 sq ft15.2 lb
OSB of the same category, 4 × 8 ft (+10%)32 sq ft66.9 lb

Species, glue and moisture move the real figure either way; hardwood-faced and MDF-core panels are not covered by APA’s table.

Span ratings made in 5/8

APA rated panels carry a span rating: the largest recommended center-to-center spacing of the supports under them, in inches, with the panel’s long side across three or more supports. On Rated Sheathing it is two numbers, roof/subfloor: a 32/16 panel may go over roof supports up to 32 in apart, or subfloor supports up to 16 in apart. On Rated Sturd-I-Floor, single-layer flooring, it is one support spacing (16 oc, 24 oc). These are the ratings APA lists in 5/8:

Next

Lay out parts on a sheet with the plywood cut list calculator. The face and back letters are explained on plywood grades, sheet sizes on plywood sizes, and the metric sheets on Baltic birch plywood. 5/8 MDF is sold at its full stated thickness; its weight is on its own page.

Work it out for your project

Sources

  1. NIST (US Department of Commerce) / APA, Voluntary Product Standard PS 1-22, Structural Plywood, §5.4, §5.10 and Table 10 (effective 2 October 2023), read 2026-11-07
  2. APA – The Engineered Wood Association, Panel Design Specification, Form D510C (revised February 2008): §2.5 span ratings, Table 5 (thickness by span rating) and Table 6 (approximate weight), read 2026-11-08

How we source these numbers