Glossary
Corrugated cardboard
Definition
A material made of one or more fluted paper layers glued between flat liners. The air-filled flutes make it light, strong and the standard for shipping boxes.
Also known as: Corrugated board, Corrugated fibreboard, Cardboard
Corrugated cardboard is the ridged, layered board used for the vast majority of shipping and postal boxes. Its defining feature is the fluted medium, a wavy paper layer glued between smooth liners. Those arches of air give the board its rigidity and cushioning while keeping weight low.
Flutes come in different profiles, labelled by letter. Fine flutes such as E and F give a smooth surface for high-quality print and slim retail boxes, B and C flutes balance print and protection for general shipping, and coarser A flute maximises cushioning. Boards can be single-wall, double-wall or triple-wall depending on how many fluted layers are combined.
Most corrugated board is made largely from recycled paper fibre and is itself widely recyclable at kerbside, which makes it a mainstay of lower-impact packaging. Strength is commonly specified by edge crush test (ECT) or bursting strength rather than by thickness alone.
What to check
- Pick a flute profile suited to print quality versus cushioning needs.
- Specify strength by ECT or bursting test, not just wall count.
- Match single, double or triple wall to product weight and handling.
- Check recycled content and kerbside recyclability if sustainability matters.
- Confirm the board copes with your storage humidity, as damp weakens it.
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Corrugated cardboard — FAQs
What do the flute letters like B, C and E mean?
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