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Flute, an instrument of strength

The flute is not an instrument that has a good moral effect - it is too exciting. – Plato

At Forest Packaging we couldn’t agree more with the philosopher from Athens – we find “flutes” - oh too exciting even if we’re talking corrugate as opposed to the instrument.

When it comes to corrugate, “flutes” are the unit of measurement used to designate thickness and strengths, commonly ranging from A-flute to F-flute.

Larger flute profiles deliver greater vertical compression strength and cushioning. Smaller flute profiles provide enhanced structural and printing capabilities for retail packaging.

Flutes are the “waves” typically sandwiched between two liner boards. These waves bring strength to paper structure. There are other types that only have one liner board and double walls, but this discussion will focus on single wall types.

Single-wall boards with B- or C-flute are the most commonly used corrugated paperboard sizes with roughly 70% of all corrugate made in the United States being C-flute.

The following descriptions cite the characteristics of each named flute and their purpose:

A-Flute: 1/4" thick, 33 flutes per linear foot

B-Flute: 1/8" thick, 47 flutes per linear foot

C-Flute: 3/16" thick, 39 flutes per linear foot

E-Flute: 1/16" thick, 90 flutes per linear foot

F-Flute: 1/32” thick, 128 flutes per linear foot


A-flute is the original corrugated flute design and is the thickest. With it's thickness , A-flute provides the greatest softening properties for fragile products. A-flute offers exceptional stiffness qualities and short column crush resistance, it has application across a broad range of customer uses.


With lower wave heights and more flutes per foot than A-flute material, B-flute contacts liners at a greater number of points. This additional support provides a stiff, flat surface for high quality printing and die cutting. B-flute offers excellent puncture and crush resistant properties, and consumes less warehouse space. Developed for packaging canned goods, B-flute is used for beverage trays, wrap-around blanks, glass-to-glass packs, and slip-sheets. It is also preferred for high speed, automatic packing lines as well as for pads, dividers, partitions, and other forms of inner packing.


C-flute is the most widely used flute size, commonly used for shipping cases. Often used for packaging glass products, dairy products, and furniture. It offers good crushing resistance, good stacking strength, and highly acceptable printing properties.


Containing about 90 flutes per foot, E-flute has greater crush resistance and a relatively flat surface for high quality printing applications. The thin board profile of E-flute reduces outer box dimensions, and can help save storage space. With its thin profile, cushioning properties, and flat surface, E-flute offers a strong alternative for conventional paperboard folding cartons including boxes for cosmetics, fragile glass, and ceramics, and delicate instruments.


Developed for small retail packaging, F-flute makes packages with lower fiber content. With reduced fiber in the packaging, a more rigid box is created with less solid waste going into landfills. In Europe, F-flute is being used for specialty packaging, point-of-purchase displays, jewelry and cosmetic packages, and shoe boxes. In the United States, fast food chains are adopting F-flute material in clamshell packaging.

Flutes per Linear Foot: 128 Thickness: 1/32"

So if you’d like to get “excited” about flutes, the friendly professionals at Forest Packaging would love to collaborate with you. Please contact me at

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