Corrugated Flute Types Explained: A, B, C, E and F Flute
The wavy layer inside corrugated board is called the flute, and its size changes how the board behaves. Knowing the corrugated flute types helps you pick board that is strong enough, prints well and suits your machines.
What a flute does
Each wave acts like a tiny arch. Taller flutes give more cushioning and stacking strength. Smaller flutes give a flatter surface and better printing. Flute size is described by letters, and the values below are approximate industry figures.
Common flute types
- A flute: the tallest of the common flutes (about 4.5 to 5 mm). Excellent cushioning and stacking strength, less flat for printing.
- C flute: medium height (about 3.5 mm). A popular all round choice for shipping cartons.
- B flute: lower (about 2.5 mm) with more flutes per length. Strong against crushing and good for die cutting and printing.
- E flute: thin (about 1.5 mm). Smooth surface for high quality print on retail and display packs.
- F flute: very thin (about 0.8 mm). Used for small, fine retail boxes.
Looking for the right machine? Tell us your requirement.
Send Inquiry →Combining flutes in 5 ply board
5 ply board uses two flute layers, often a combination such as B and C. This balances cushioning with rigidity and gives stronger, thicker board than single flute 3 ply.
How flute choice affects your machines
The flute profile is formed by the grooved corrugating rollers, so each flute type needs matching rollers. If you plan to make more than one flute, check whether the machine supports roller change or a double profile design, such as our double profile single facer. Learn more about the rollers in our roller guide.
Quick selection guide
- Heavy or fragile goods: A or C flute, or 5 ply.
- General shipping boxes: B or C flute.
- Printed retail packaging: E or F flute.
Frequently asked questions
Which flute is strongest?
Taller flutes such as A give more stacking strength and cushioning, while B flute resists crushing well. The best choice depends on use.
Which flute prints best?
E and F flutes have a smoother surface and suit fine printing.
Can one machine make all flutes?
Only if the rollers and design support it. Each flute normally needs its own roller profile.
