When packaging your product, the size and shape of your corrugated box are not the only considerations. Corrugated flute size also plays an essential role in protecting your product. Using the wrong flute size could leave your product vulnerable to damage or, conversely, use more material than is needed creating heavier, bulkier packaging or impacting the print quality. Some flutes provide greater vertical compression strength and cushioning, while others provide enhanced structural and printing capabilities. Understanding flutes will help you ensure the right ones are being used for your packaging.
Corrugated Flutes Explained
Corrugated board is made up of linerboard (the outside sheets) and the medium, which is the inner wavy sheet known as fluting. When combined with the linerboard and adhesive, it’s those rigid arches that allow the corrugated board to sustain a lot of weight when it is applied perpendicularly to the flute columns. Cushioning protection is provided by the space within the flutes. Understandably, larger flutes will provide greater strength. Small flutes, which are closer together, have the benefit of delivering better printability and foldability.
Understanding Corrugated Flute Profiles
While flute measurements can vary from manufacturer to manufacturer, they are generally close. There are five common flute types: A, B, C, E, F.
It should be noted that the letter designation was assigned based on the order they were created and not the flute size.
Flutes Per Foot
|Flute Height (in)|
A-flute is the original flute design, and it is also the thickest. It provides the most cushioning and vertical compression strength and is used for transit protection. However, the far spacing of the flutes makes them unsuitable for intricate packaging designs.
B-flute has more flutes per foot than A-flute, but the flutes have a shorter height, giving it excellent puncture and crush-resistant properties. The closer flutes make it smoother for printing. This flute was developed for shipping canned goods, but it is also used for inner packing, such as pads and dividers.
C-flute is the most common corrugated fluting for shipping boxes. It is thicker than B- flute, and it provides good crush resistance and stacking strength as well as acceptable print characteristics.
E-flute and F-flute are considered micro-flutes because of their thinness. E-flute has excellent crush resistance, and because of its relatively flat surface, high-quality printing is possible. E-flute is now being used more to replace retail folding cartons, which offer very little protection. E-flute’s crush resistance and printability make it a great choice to protect the product and deliver a blank canvas for exceptional branding opportunities. Although E-flute can reduce outer box dimensions, it doesn’t offer puncture protection, so it is not recommended for heavy objects.
F-flute was developed for small retail packaging and is sometimes used interchangeably with E-flute. It is half the thickness of E-Flute but has greater flute density – about 30 percent more flutes per foot and provides an excellent surface for printing applications. F-flute is often used for fast food clamshell packaging as it provides thermal qualities keeping food hot.
Still Not Sure What Corrugated Flute Your Product Needs?
We have in-house structural and graphic designers that will collaborate with you to ensure your packaging meets your expectations. With over 100 years of combined experience, our structural designers have experience working with various materials and comprehensively understanding in-store packaging requirements for major retail channels, consumer-product relationships, and supply chain factors. Our in-house graphic designers work closely with the structural design team to create and adapt branded visual packaging solutions.