Corrugated cardboard is a layered board made of a fluted, wavy inner sheet glued between one or more flat outer liners. Those flutes are what give it strength and cushioning, which is why corrugated is the standard material for shipping boxes and mailers rather than the thin paperboard used for retail cartons.
The anatomy of a corrugated board
A corrugated board has two parts: the liner, which is the flat facing you print on, and the flute, which is the wavy layer in the middle. The flute acts like a row of arches, absorbing impact and resisting crushing. Add more liners and flutes and the board gets stronger.
Single wall vs double wall
Single wall corrugated has one fluted layer between two liners and covers most ecommerce and retail shipping. Double wall corrugated has two fluted layers and three liners for heavy or fragile goods that need extra protection in transit.
Flute grades
Flutes are graded by size. C flute is the common all rounder for shipping boxes. B flute is thinner and better for retail and die cut boxes. E and F flutes are very fine and used for small printed cartons where a smooth print surface matters. A flute is the thickest, used where cushioning is the priority. For the published figures, flutes per foot, the ECT and Mullen carrier tables and the caliper conversions, see our corrugated board specifications reference.
Uses and recyclability
Corrugated is used for mailer boxes, shipping boxes, and shelf ready trays. It is also widely recyclable and available in recycled content, which makes it a practical choice for brands that want a sustainable shipping option. Browse our corrugated boxes, custom corrugated boxes, and kraft corrugated boxes, all printed with no minimum order.
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