Plywood are graded as A, B, C, D, CDX or BCX. In general, the quality ranges from A being the best to D being the worst. In addition, plywood sometimes comes with a dual grade, such as AB or BB, representing the grade on each side of the panel.

Grade A
The highest quality grade of plywood is Grade A. In terms of sheet quality, this is the best option. Grade A plywood is smooth and sanded, with fine grain structure throughout the entire board. There are no holes or voids across the entire sanded face, making this grade extremely paintable.

Grade B
Grade B begins to allow for more natural grain, larger unrepaired knots, and sporadic voids. Closed knots up to 1 inch in diameter are allowed. This grade also allows for very minor splits and discoloration of the board. Many applications use grade B plywood, including cabinets and furniture.

Grade C
Grade C, much like grade B, allows for holes, voids, and knots. Closed knots up to 1 ½” in diameter are allowed, and knotholes up to 1” in diameter are allowed.

Grade D
Grade D wood is very rustic in appearance, featuring knots and knotholes up to 2 ½” in diameter, major splitting, and heavy discoloration. Grade D still requires the board to withstand stresses and loads so that it can be used safely in woodworking projects or large construction.

Grade BCX
BCX plywood is also commonly found in the plywood section. This grade uses grade C plies and a single grade B ply on one face. The adhesives used are also moisture resistant.

Grade CDX
One side is made from grade C veneer, while the other side is made from grade D veneer. Sometimes, the rest of the inner plies are made with grade D veneer to make it more affordable.This grade is optimal where large quantities of plywood are needed and most of it will be covered up anyway. CDX plywood is commonly used for exterior walls and sheathing.