How to Choose the Ideal Fluting Size

January 25, 2018

The foundation of any corrugated box starts with fluting. In fact, fluting is what makes corrugated board, corrugated. Fluting is the wavy layer of paper in the middle of corrugated board that makes boxes rigid, strong, and stackable. Adjusting your fluting can affect the size and dimensions of your shipments which could have a major effect on your product safety and shipping costs.

Flutes come in various sizes, also known as "profiles," and each one designated by letter. Get to know the different flute profiles used on shipping boxes and how to pick the best one for shipping your product.

Fluting Profiles

A Flute: The thickest flute. It's ideal for extra cushioning and shock absorption. Because of the amount of space between flutes, the board surface is less smooth, so it’s not ideal for printing intricate designs.

C Flute: The standard flute for RSC boxes, "Regular Slotted Containers," the most common style of corrugated box. It's good for stacking, strength, and crush resistance. (C flute is the second thickest flute, despite the fact that “C” comes after “B” in the alphabet. Go figure.)

B Flute: The most common flute for shipping boxes. It's a happy medium for durability and printability. Its shorter flutes make it smoother for printing, and its thickness gives it some extra cushion from any puncturing. This is what we use for most of the mailer boxes ordered at Lumi.

D Flute: Not an industry standard. Most examples of D Flute are specific to certain manufacturers that brand it with their own specifications, Typically it is a thinner alternative to B and C with a smooth print surface.

E Flute: Thin fluting profile that provides a great printing surface and it’s easy to fold. It has great crush resistance, but subpar puncture resistance, so it’s not ideal for shipping very rigid, large, or heavy products.

F Flute: Also called "micro-flute". F is half the thickness of E, but what it lacks in depth, it makes up for in flute density, so sometimes E and F flutes can be used interchangeably. F has about 30% more flutes per foot.

Fluting Specs
Flute Flutes per foot Flute thickness (inches)

Exact dimensions vary by manufacturer.

Other Factors in Fluting

Standard boxes are made of single wall corrugated which means that it’s made of one layer of fluting, sandwiched between two sheets of linerboard. For more support, you can add an extra layer of corrugated board to make it a double wall or even triple wall.

Think of fluting as a tool that you can use to customize to optimize your packaging. And if you want more information on the restrictions of a sheet of corrugated board or you want to know how it’s been tested, just flip over a box and check out the Box Maker's Certificate on the bottom. To see these fluting profiles in action, watch this episode of Shipping Things.

Ready to customize your shipping solution down to the flute? Request a Quote.

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