Corrugated Fluting Basics

One way corrugated is classified is based on flute size. There are several different sizes of fluting. Flute size affects cushioning and printability, but it does not determine strength, weight, or cost by itself. Smaller flutes also provide a better printing surface when compared to larger flutes. This is because there are more flutes per linear foot which creates a more rigid, smooth, and consistent surface for printing.

Each corrugated fluting size has its own function and features. Below is an overview of each flute size, highlighting some of its properties. You can also check out our packaging resource charts for some additional visuals. The thicknesses below are nominal trade sizes; actual board thickness varies by mill, flute profile, and liner weight.

A Flute: 1/4″ Thick (33 flutes/ft)

The largest flute profile among the A, B, C, and E sizes covered here. A flute corrugated provides an abundance of strength, cushioning, and impact resistance. A flute can be used for large items that need cushioning and impact protection, but it is not very common and minimum order quantities may apply. C, B, and E are by far the most common flute options we work with.

C Flute: 3/16″ Thick (39 flutes/ft)

The most common flute size as it has a great balance between cost and performance. Even though it is not the thickest flute size, it still provides adequate strength and impact-resistance for most applications. C flute also has a better surface for printing than A flute. C flute is commonly used for regular slotted containers because it offers a useful balance of cushioning, stacking performance, and printability.

B Flute: 1/8″ Thick (47 flutes/ft)

The “Jack of all trades, master of none” of the corrugated industry. B flute offers a useful balance of cushioning, board thickness, and printability. B flute provides a good printing surface, however, E flute would be superior. That being said, B flute is PAX Solutions’ favorite flute because of its flexibility and above-average performance. 

E Flute: 1/16″ Thick (90 flutes/ft)

One of the thinner flute options. Using the nominal sizes listed here, E flute is about one-third the thickness of C flute. Its thinner profile can reduce storage space. E flute also provides great printability as the small flutes help keep the board straight for consistent printing. E flute is best used for packaging smaller, light-weight items that are not easily breakable.