Walk through any lumberyard and you will see plywood stacked in a handful of standard thicknesses: 1/8, 1/4, 3/8, 1/2, 5/8, and 3/4 inch. Those labels describe the panel in general terms, but the sheet you take home rarely measures exactly what the sticker says. A panel sold as 3/4 inch often comes out of the stack at 23/32 inch, and a sanded 1/2-inch panel typically lands at 15/32 inch. The gap between the nominal size and the actual size changes how you set up joinery, what blade you reach for, and how you plan each cut, so a reliable cutting plywood to size method pays off on every project. Once you know what you are actually holding, every later decision, from fasteners to framing spacing, gets easier.
The Standard Plywood Thickness Chart
Plywood thickness naming follows a convention that predates modern sanding lines. The chart below lists the most common nominal sizes, the actual thickness you can expect from a sanded panel, the rough measurement of an unsanded sheathing panel, and the jobs each size handles best. Hardwood plywood sold for cabinets follows the same nominal system as softwood sheathing, so the same fractions apply at the cabinet shop and the framing yard.
| Nominal size | Sanded panel | Sheathing panel | Typical uses |
|---|---|---|---|
| 1/8 inch | 1/8 inch (0.125) | 1/8 inch | Craft projects, small box sides, backs |
| 1/4 inch | 1/4 inch (0.250) | 7/32 inch | Drawer bottoms, cabinet backs, wainscoting |
| 3/8 inch | 11/32 inch (0.344) | 3/8 inch | Light shelving, paneling, gussets |
| 1/2 inch | 15/32 inch (0.469) | 1/2 inch | Wall sheathing, shelving, cabinet casework |
| 5/8 inch | 19/32 inch (0.594) | 5/8 inch | Heavy shelving, work surfaces |
| 3/4 inch | 23/32 inch (0.719) | 3/4 inch | Subflooring, wall framing, furniture, countertops |
Two details in the table deserve a second look. Sanded panels come in thinner than their nominal size because the faces are machined after pressing, while unsanded sheathing often runs full size, so a 3/4-inch CDX panel really is close to 0.75 inch. When you compare modern panel systems, the facing and the core both change the final dimension, and zip system sheathing vs plywood comparisons make the trade-off easy to see: one product wraps the panel in a coated face, the other relies on layered veneers, and each approach measures up differently at the job site.
Why a 3/4-Inch Sheet Measures 23/32 Inch
Three forces push plywood away from its label. Sanding removes material from the face veneers to smooth the surface, so a panel that starts at 0.75 inch can end up at 23/32 inch by the time the last pass finishes. Manufacturing tolerances written into the ANSI PS 1 and PS 2 standards allow a sanded panel to vary by roughly 1/32 inch from its target. Metric production adds a third variable: panels made to 18 mm, 12 mm, and 6 mm dimensions convert to about 0.709, 0.472, and 0.236 inch, which is why a metric sheet is not interchangeable with a fractional one at the lumberyard.
Sanded plywood versus sheathing
Sanded panels such as ACX and cabinet-grade birch get the full machining treatment and come out under nominal size. Sheathing grades such as CDX skip that step and stay closer to their stated dimension. The trade-off is surface quality: a sanded face takes paint and veneer well, while an unsanded sheathing face shows grain and voids that need filling before finish.
- Sanded panels: thinner than nominal, smooth faces, right for visible work
- Sheathing panels: closer to full dimension, rougher faces, right for structure
- Metric panels: dimensioned in millimeters and usually under the fractional equivalent
This is also where plywood and MDF diverge. MDF is pressed from wood fiber and resin into a slab with tightly controlled thickness, so an 18 mm board is almost always 18 mm. Plywood is built from layered veneers and calibrated after pressing. The difference between MDF and plywood shows up right here: one is engineered for dimensional consistency, the other for strength and stability, and each behaves differently when you route an edge or sink a screw into it.
Choosing Plywood Thickness by Job
The right thickness depends on the span, the load, and whether the panel will be visible. Residential construction has settled on a few standard choices worth memorizing, and they line up with the joist and rafter spacing used in most framing.
Structural applications
- Subflooring: 3/4-inch plywood on joists spaced 16 or 19.2 inches on center
- Wall sheathing: 1/2-inch plywood on studs at 16 or 24 inches on center
- Roof sheathing: 1/2 inch for most asphalt shingle roofs, 5/8 inch where heavier tile or standing seam roofing is planned
- Single-layer flooring: 3/4-inch tongue-and-groove plywood or OSB
What the span rating numbers mean
Look at the stamp on a structural panel and you will see a pair of numbers such as 32/16 or 48/24. The first number is the maximum rafter spacing in inches for roof use; the second is the maximum floor joist spacing. A 7/16-inch panel stamped 24/16 works for rafters spaced 24 inches apart but floors spaced only 16 inches apart, so the rating matters more than the label thickness when you choose roof and floor sheathing.
For buildings that push panels harder, engineered assemblies carry loads a standard sheet cannot. Some modern designs laminate several layers of high-grade plywood together, and the same thinking shows up in high-strength wood panel buildings, where panel thickness and grain orientation are engineered rather than guessed. If your project has unusual loads or long spans, treat the thickness chart as a starting point, not a final answer.
- Check the span rating stamped on the panel
- Match the thickness to the spacing of your joists or rafters
- Upgrade to 3/4 inch wherever heavy loads or wide spacing appear
- Confirm the exposure rating for exterior or damp locations
How to Measure Plywood Thickness at the Store
Plywood tolerances mean the panel you grab off the rack can differ from the panel next to it. A few minutes of checking at the store prevents fit problems later in the shop.
Use a caliper, not a tape measure
A tape measure reads the nearest 1/16 inch if you are lucky. A caliper reads to 1/1000 inch, which is the resolution you need to compare a 23/32 panel against a 3/4 dado. Measure at the edge in at least three places: both ends and the middle. Panels that sat in a damp stack can swell at the ends, so the middle measurement is often the most honest one.
Read the grade stamp
The APA stamp on the panel tells you the exposure rating, the span rating, and the mill. The letters describe the face and back veneers: A is smooth and sanded, B is solid with minor repairs, C allows small knots, and D allows larger knots and voids. A CDX panel has a C face, a D back, and exterior glue, which makes it fine for sheathing but rough for furniture.
The measuring habit pays off when you build with the sheet. Shop furniture is especially sensitive to real thickness because joints, fasteners, and edge treatments all reference the actual panel dimension, and a typical sturdy shop table built from plywood relies on 3/4-inch material that is exactly what the plans assume. Measure first, cut second.
Working with Different Thicknesses
Each thickness range rewards a slightly different technique, and a little planning at the saw pays for itself in clean joints.
Cutting and joining by thickness
- 1/4-inch panels: use fine-tooth blades, keep dado cuts shallower than the panel, and reinforce joints with glue blocks
- 3/8 and 1/2-inch panels: support the sheet during cutting to prevent chatter; pocket screws work when the screw length stays under the panel depth
- 3/4-inch panels: accept standard joinery including dados, rabbets, and structural screws; check that screws sized for 3/4 material do not poke through when the panel measures 23/32
Bending plywood around curves
Thin plywood bends and thick plywood breaks. Panels 1/8 and 1/4 inch thick follow gentle curves, which is why curved furniture and barrel forms use them. For tighter radii, bent lamination with several thin layers performs better than a single thicker sheet. Structural curves take a different route: trusses and plywood gussets carry curved roofs without trying to bend full sheets, and the gusset thickness is chosen to match the load, not the curve.
Planning Around Real Panel Thickness
The practical takeaway is simple: design with the actual thickness, not the label. When a plan calls for 3/4-inch plywood and your panel measures 23/32 inch, adjust dado widths, fastener lengths, and reveal lines before assembly. Buy from the same stack when a project needs matching thickness, and keep offcuts organized because they carry real value.
Scrap management is where small panels earn their keep. Leftover 1/4-inch sheets become jig bases and drawer dividers, while 3/4-inch offcuts turn into sawhorses, clamping cauls, and job site storage; a popular project, building a tool tote from scrap plywood, turns material that would otherwise hit the dumpster into something used daily. Nominal sizes give you the vocabulary, actual measurements give you the fit, and a caliper in the truck means neither one surprises you at the cut line.