How to Choose the Right GSM Paper for Your Packaging
What GSM actually measures, how it differs from burst factor and kraft quality, and why a higher GSM figure does not automatically mean a stronger box.
GSM stands for grams per square metre and measures the weight of the paper used in the liners and the fluting medium of a corrugated board. It is one of the most quoted numbers in a packaging specification, and one of the most misunderstood. GSM tells you how heavy the paper is; it does not, on its own, tell you how strong the finished box will be.
Corrugated board is built from two components: liner (the flat outer and inner layers) and medium (the fluted layer in between). Each can carry a different GSM, and the combination — along with the paper quality itself — determines how the box performs under compression, puncture and handling.
GSM, burst factor and paper quality are not the same thing
Two liners at the same GSM can behave very differently under load if one is made from stronger virgin kraft fibre and the other from a weaker recycled furnish. GSM tells you weight; burst factor and edge crush values tell you strength.
Burst factor (BF) reflects the bursting strength per unit weight of the paper and is a better indicator of quality than GSM alone. A 150 GSM liner with a high BF can outperform a 180 GSM liner of lower fibre quality. When comparing quotes, ask for both figures rather than GSM in isolation — a supplier can hit a GSM target with cheaper fibre and still fall short on strength.
Typical combinations by load
| Load type | Typical liner GSM | Typical medium GSM | Example use |
|---|---|---|---|
| Light | 100–120 GSM | 100–120 GSM | Garments, small retail cartons, light electronics accessories |
| Medium | 150–180 GSM | 120–150 GSM | General industrial goods, mid-weight auto parts, export cartons |
| Heavy | 200–250 GSM and above | 150–180 GSM | Machinery components, dense metal parts, heavy palletised loads |
Why higher GSM is not always the answer
- A heavier liner adds cost and shipping weight without improving performance if the flute profile or box construction is the weak point.
- GSM has no bearing on moisture resistance on its own; a treated or better-quality kraft liner will hold up in humid coastal storage better than an untreated heavier one.
- Overspecifying GSM to compensate for a poor box design masks the real problem and adds recurring cost to every order.
- The right combination of liner GSM, medium GSM and ply count together determines bursting strength and compression resistance — changing one figure in isolation rarely fixes a performance issue.
We test GSM, bursting strength, ply bond and moisture content in-house on every batch, so if a current specification is underperforming, send us a sample or the specification sheet and we can identify whether GSM, paper quality or construction is the actual gap.
Not sure if your GSM specification is right?
Send us your current board specification or a sample and we will check the GSM, burst factor and construction against your load requirement.
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