Caliper
The thickness of a sheet of board, usually given in inches or millimetres.
In practice
Caliper matters twice: it sets how much bigger the outside of a box is than the inside, and it sits under the square root in the McKee formula, so thicker board stacks better at the same ECT.
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Related terms
- Flute
- The wave-shaped medium inside corrugated board, and the size class of that wave (A, B, C, E, F).
- Inside dimensions
- The usable space inside a box, listed length × width × depth. Box sizes are quoted by inside dimension.
- Outside dimensions
- The box's outer size, which carriers measure for dimensional weight and which sets pallet patterns.
- McKee formula
- An equation from McKee, Gander and Wachuta (1963) that estimates box compression strength from edge crush, caliper and perimeter.
Definitions written by Packgent, last reviewed 2026-10-27. All terms.