Plywood Grade Converter
Look up plywood grade letters, descriptions, and standard thicknesses.
Compare grades A through D and their recommended uses.
Select a plywood grade or thickness to see details and recommended uses.
Plywood is graded by the quality of its face and back veneers, using letters A through D. The grade is written as two letters: the first is the face quality, the second is the back quality (e.g., A-C means A-grade face, C-grade back).
Plywood veneer grades:
| Grade | Quality | Description |
|---|---|---|
| A | Premium | Smooth, sanded, paintable. Minimal repairs visible. Suitable for visible surfaces. |
| B | Good | Solid surface with minor repairs, small knots, and patches allowed. Can be painted. |
| C | Utility | Knotholes up to 1.5 inches, some splits. Good for structural use where appearance does not matter. |
| C-Plugged | Improved utility | Better than C, knotholes filled with patches. Used as underlayment. |
| D | Economy | Large knotholes, splits, and defects allowed. For interior structural use only. |
Common plywood grade combinations and uses:
| Grade | Typical Use |
|---|---|
| A-A | Cabinet doors, furniture, visible both sides |
| A-B | Cabinet sides, shelving (one good side visible) |
| A-C | Siding, exterior projects (one finished side) |
| B-C | Utility shelving, backing, subflooring |
| C-C (CDX) | Roof sheathing, subflooring, exterior structural |
| C-D | Wall sheathing, temporary construction |
Standard plywood thicknesses:
| Nominal (inches) | Actual (inches) | Actual (mm) |
|---|---|---|
| 1/4" | 7/32" (0.219") | 5.6 |
| 3/8" | 11/32" (0.344") | 8.7 |
| 1/2" | 15/32" (0.469") | 11.9 |
| 5/8" | 19/32" (0.594") | 15.1 |
| 3/4" | 23/32" (0.719") | 18.3 |
| 1" | 31/32" (0.969") | 24.6 |
The pattern is simply nominal minus 1/32 inch, lost to sanding and manufacturing tolerance. It is why panels are now labeled by “Performance Category” instead: a sheet stamped 23/32 is what everyone still calls three-quarter-inch plywood.
Imported metric plywood, including most Baltic birch, is a different series and does not line up with any of this. It comes in 6, 9, 12, 15 and 18 mm. An 18 mm sheet is about 0.01 inch thinner than a 23/32 inch domestic sheet, which sounds like nothing until you cut a dado for one and try to fit the other. Measure the sheet in front of you before you cut the joint.
Exposure ratings (separate from veneer grade):
- Exterior: Waterproof glue, suitable for permanent outdoor exposure.
- Exposure 1: Moisture-resistant glue, handles temporary exposure during construction but not permanent outdoor use.
- Interior: Not moisture-resistant, for indoor use only.
CDX explained: CDX is the most commonly sold plywood. “CD” means C-grade face, D-grade back. The “X” stands for Exposure 1 rating (not Exterior), meaning it can handle temporary moisture during construction.
Practical tip: For painted furniture and cabinets, B-grade plywood with wood filler and sanding produces a finish nearly as good as A-grade at a significantly lower cost.
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