Corrugated boxes are made of corrugated board that consists of two main components: the linerboard and the medium, both of which are constructed from a heavy paper called containerboard. The flat linerboard is adhered to the wavy, fluted medium to form either a single wall or double wall corrugated board.



Single Wall

In single wall board, one layer of the fluted medium is placed between two sheets of linerboard. The outside liner is generally smoother than the inside liner, which is more rippled.



Double Wall

In double wall board, two layers of the fluted medium are alternately placed between three sheets of linerboard. The outside liner is smoother than the inside liner, and the outside corrugated medium is more compact than the inside corrugated medium. Double wall board is used for packaging heavy items that may require increased protection and box rigidity.


Flute Types

The wavy shapes that give the corrugated medium its strength are known as flutes. When adhered to the linerboard, these flutes resist bending and pressure from all directions. The different flute styles provide a range of cushioning, stacking strength and printability to meet any need. Generally, larger flutes provide greater strength and cushioning, while smaller flutes have better printing surfaces and are easier to fold.


Flute Profile Flutes/foot Thickness Characteristics
A a_fluting.gif 36 1/4″
  • The tallest, thickest and strongest of the flute profiles
  • Offers excellent cushioning and stacking qualities
  • Often used for packaging fragile, delicate items
B b_fluting.gif 49 1/8″
  • Lower arch heights than A and more flutes per foot
  • Provides a stiff, flat surface for high-quality printing
  • Excellent crush and puncture resistance
  • Folds better than A and C flutes
  • Commonly used for die cut boxes and shipping containers
C c_fluting.gif 41 5/32″
  • Thinner than A and thicker than B
  • Offers good cushioning and stacking properties
  • Used to construct an estimated 80 percent of corrugated containers, making it the most widely used flute style
  • Commonly used for shipping containers
E e_fluting.gif 95 1/16″
  • Large number of flutes per foot
  • Has the greatest crush resistance
  • Has the flattest surface for superior printing
  • Thin profile (one fourth the thickness of A) reduces bulk and saves storage space
  • Very lightweight
  • Often used in retail packaging and small die cut boxes
BC bc_fluting.gif NA 1/4″
  • Combines B and C flutes to form a double wall corrugated board
  • Provides extra cushioning and stacking strength
  • Often used for packaging heavy items