What do GSM and flute mean?
GSM (grams per square metre) measures how heavy — and roughly how thick and stiff — a paper or board is. Flute describes the wavy middle layer of corrugated board; different flute sizes trade print quality for cushioning and strength.
Common paperboard types
| Duplex board | Coated white top with a grey back. Cost-effective and widely used for cartons in FMCG, pharma and food. |
|---|---|
| SBS / FBB | White on both sides with a smoother surface. Better print quality and a more premium look — common in cosmetics and premium retail. |
| Kraft board | Natural brown, strong and recyclable, with an earthy, sustainable feel. |
| Greyboard | Thick, rigid board used as the core of rigid boxes, wrapped in printed or speciality paper. |
| Speciality papers | Textured, metallic, linen or coloured papers used as wraps for luxury packaging. |
How to think about GSM
Higher GSM generally means a stiffer, more substantial board. Light cartons for small products use lower GSM board, while larger or heavier products need higher GSM for strength. The right choice balances protection, feel and cost — your packaging partner should recommend it based on product weight and box size.
Corrugated board: ply and flutes
- 3-ply — one fluted layer between two liners. Suits lightweight products and mailers.
- 5-ply — two fluted layers. Stronger, for heavier products and shipping cartons.
- 7-ply — three fluted layers. Heavy-duty and industrial use.
| E-flute | Thin flute with a smooth surface — excellent for printed mailer boxes and retail-ready packaging. |
|---|---|
| B-flute | A good all-rounder with better crush resistance. |
| C-flute | Thicker flute with more cushioning and stacking strength — common for shipping cartons. |
Choosing the right material
Start from how the product travels and how premium it must look. Shelf cartons favour smooth SBS or duplex; courier shipments need corrugated; luxury gifting calls for greyboard with speciality wraps. Ask us for a material recommendation →
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