What a Grade Is Based On
Used box grades are a common shorthand, not an official standard. Different sellers use different wording, but most look at the same three things: structure, surface condition, and specifications. Knowing what they look at lets you check a sample yourself.
Structural Integrity
Walls. Firm walls with no soft spots, separation between layers, or water damage.
Corners. Corners carry much of the stacking load, so crushing or splitting matters.
Bottom flaps. The bottom holds the weight. Flaps should be intact and fold without cracking.
Top flaps. Flaps should fold closed properly. Badly bent or missing flaps usually mean a low grade or a reject.
Surface Condition
Printing and labels. The cleanest grades usually have little or no printing or labels, while lower grades may be heavily covered.
Tape and adhesive residue. Light residue is cosmetic. Tape that has torn away the liner is more serious.
Staining. Water stains, oil marks, or discoloration lower a grade, and heavy staining is often a reason to reject a box.
Odor. A box that smells of chemicals, food, or mildew is usually not fit for reuse.
Specifications
Dimensions. A box should match the size it is sold as, and it helps to know whether that size is inner or outer.
Wall type. Single, double, or triple wall can be confirmed by looking at the cut edge of the board.
Box certificate. If the stamp on the bottom flap is legible, it shows the original ECT or burst rating.
Grades are general, and a supplier decides how to apply them. Before ordering in quantity, ask a partner supplier how its grades are defined, and inspect a sample against the list above.