1-1/8 plywood: actual thickness and weight
Sanded panel measures
1.091–1.159 in
27.71–29.44 mm
From the standard, NIST PS 1-22
A 4 × 8 ft sheet weighs about
105.6 lb
3.3 lb per square foot
One source: APA – The Engineered Wood Association, the trade association that publishes the panel design specification
How thick 1-1/8 plywood really is
1-1/8 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 1-1/8 in; it gives a range. Sanded panels, the smooth faces sold for cabinets and furniture, are held to a tighter range than unsanded sheathing.
| Panel | Inches | Millimetres |
|---|---|---|
| Sanded | 1.091–1.159 | 27.71–29.44 |
| Unsanded, touch-sanded or overlaid | 1.069–1.181 | 27.15–30 |
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 1-1/8 plywood weighs
APA gives 3.3 lb per square foot as the approximate weight of 1-1/8 plywood for working out dead loads, and says to add 10% for OSB. A sheet is that weight times its area.
| Piece | Area | About |
|---|---|---|
| Full sheet, 4 × 8 ft | 32 sq ft | 105.6 lb |
| Half sheet, 4 × 4 ft | 16 sq ft | 52.8 lb |
| Quarter sheet, 2 × 4 ft | 8 sq ft | 26.4 lb |
| OSB of the same category, 4 × 8 ft (+10%) | 32 sq ft | 116.2 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 1-1/8
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 Sturd-I-Floor, single-layer flooring, it is one support spacing (16 oc, 24 oc). These are the ratings APA lists in 1-1/8:
- Rated Sturd-I-Floor 48 oc
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. MDF thicknesses and weights are on the MDF thickness chart.
Work it out for your project
- Estimate the lumber for a whole project
List the parts, get the boards and board feet to buy, with waste.
Sources
- 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
- 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