Open any corrugated box and you'll find a wavy paper layer sandwiched between flat liners. That wave is called the flute, and its size changes everything about how the box performs. Choosing the right flute is one of the simplest ways to improve protection or cut packaging cost.
How flutes work
The arched shape of a flute does two jobs at once:
- The arches act like tiny columns, resisting top-to-bottom compression (stacking strength).
- The air gaps between arches act as cushioning and insulation.
More flutes per metre means a smoother, thinner board that prints well. Fewer, taller flutes mean a thicker board with more cushioning.
The common flute profiles
| Flute | Approx. thickness | Flutes per metre | Best for |
|---|---|---|---|
| A | ~5 mm | ~110 | Maximum cushioning & stacking strength; fragile, heavy items |
| C | ~4 mm | ~130 | The all-rounder — shipping boxes for most products |
| B | ~3 mm | ~150 | Good crush resistance, flat print surface; canned/retail goods |
| E | ~1.5 mm | ~290 | Thin, rigid, excellent print; retail & e-commerce boxes |
| F | ~0.8 mm | ~420 | Very thin; premium small retail packaging |
A-flute
The tallest common flute. Best cushioning and stacking performance — ideal for fragile or heavy products that need shock absorption.
C-flute
The workhorse of shipping. A balance of cushioning, stacking strength and printability. If you're not sure, C-flute is usually the safe default for a regular shipping carton.
B-flute
Thinner and firmer, with great resistance to crushing on flat surfaces and a smoother face for printing. Common for canned goods, books and retail-ready boxes.
E-flute and F-flute
Very thin and rigid with an excellent print surface — the go-to for e-commerce mailers and retail packaging where shelf appearance matters and the product isn't heavy.
Combining flutes: double and triple wall
For heavier loads, two or three fluted layers are combined:
- BC double wall — pairs B-flute's flat strength with C-flute's cushioning. Excellent for export and heavier shipments.
- EB double wall — print quality plus protection for premium retail.
- Triple wall — three fluted layers for industrial, machinery and bulk loads that would otherwise need a wooden crate.
A quick decision shortcut
- Shipping a typical product? → C-flute.
- Fragile or heavy? → A-flute, or BC double wall.
- Retail / e-commerce where print matters? → E-flute.
- Industrial / very heavy? → Triple wall.
The right flute can shave material cost while improving protection — or the wrong one can quietly cost you in damages and returns. Send us your product details and we'll recommend the optimal board.
