Corrugated Flute Types: A, B, C, E and F
The flute is the wavy layer glued between the flat liners of corrugated board. Flute types are named by letter. Taller flutes such as A and C cushion and stack better. Shorter flutes such as B, E and F make thinner, stiffer board that prints well and suits retail packaging.
Quick reference
| Flute | Approx height | Feel | Common use |
|---|---|---|---|
| A | Around 4.5 to 5 mm | Thick, springy | Cushioning, fragile goods |
| B | Around 2.5 to 3 mm | Thin, stiff | Die-cut boxes, inner packs |
| C | Around 3.5 to 4 mm | Balanced | Standard shipping cartons |
| E | Around 1.1 to 1.5 mm | Fine, smooth | Retail and printed packs |
| F | Under about 1 mm | Very fine | Premium retail, small packs |
Heights vary slightly unit to unit, so treat the numbers as working ranges rather than exact specifications.
How flute choice plays out
- Shipping cartons in India commonly run on C or B flute, or both together in a 5 ply board.
- Retail and mailer style boxes lean on E or B flute for sharp folding and clean print.
- Fragile products like glassware favour taller flutes for cushioning, often with inserts.
Combining flutes
A 5 ply board carries two flutes, and mixing them is normal practice. A common build pairs a taller flute for cushioning with a shorter one for stiffness, giving a wall that protects and stacks at the same time. Tell the unit what the box must survive, and let the flute combination follow from that.
Frequently asked questions
Which flute is strongest?
For stacking, taller flutes like A and C do well. For flat crush and print surface, shorter flutes win. Strength depends on the job.
Can I feel the difference by hand?
Yes. Count the waves along a cut edge: fine, dense waves mean E or F, big open waves mean A.
Does flute choice change price?
It changes paper consumption and machine setup, so yes, moderately.