How to Choose the Right Paper GSM for Packaging

Overview

Choosing the right paper weight is one of the most important decisions in packaging. GSM, which means grams per square meter, describes the density of the paper or board and directly affects stiffness, print quality, protection and cost. A stock that is too light can make a pack feel cheap, while a stock that is too heavy adds material and freight cost without improving the customer experience. Getting the weight right is the foundation of a pack that feels and performs as intended.

What GSM Actually Means

GSM measures the mass of one square meter of paper. Higher numbers mean thicker, heavier stock: a 90 gsm sheet is thin and flexible, while 350 gsm board is stiff enough to stand as a card. GSM alone does not tell the whole story, because two papers of the same weight can perform differently depending on fibre type, coating and bulk. Always ask for a physical sample together with the GSM figure so you can judge stiffness and feel by hand.

Matching GSM to the Application

Business cards and inserts often use 300 to 400 gsm coated stock. Product cartons for cosmetics and electronics frequently use 300 to 350 gsm art paper laminated to 1000 to 1400 gsm grey board for a rigid feel. Light retail cartons that only protect small items can use 250 to 300 gsm folding boxboard. Paper bags range from about 100 gsm for promotional use to 210 gsm for a premium handle bag. Shipping cartons are usually specified by flute profile rather than GSM, because the corrugated medium and liners work together to carry the load.

Coatings, Medium and Bulk

Coated papers accept fine detail and vivid images, while uncoated kraft stock communicates a natural, recycled look. Bulk, the thickness for a given weight, matters for rigid boxes because a high-bulk board feels more substantial at the same GSM. For food contact, confirm that the board is food grade and that any coating is approved for the intended use.

Practical Checklist

Confirm the finished size and the load the pack must carry. Decide how much rigidity the brand requires. Request samples at two GSM levels and compare them by hand. Check that the stock suits your print process and finishing. Finally, balance the specification against freight and unit cost, since heavier board raises both. Choosing paper is a balance of feel, protection and budget, and sampling with your supplier is the fastest way to confirm the right choice.

Key figures and tolerances

• Folding carton board: 200–250 g/m² for light retail packs, 300–450 g/m² for premium or heavy items (grammage per ISO 536).
• Caliper: 200 g/m² is typically 250–300 µm and 350 g/m² about 400–450 µm (ISO 534).
• Bulk: bulky board 1.4–1.8 cm³/g, dense SBS 1.2–1.4 cm³/g (ISO 534).
• Moisture content: 5–8% (ISO 287); below 4% board becomes brittle, above 9% it waves and misregisters.
• Grammage tolerance: ±3–5% between reels and batches (ISO 536).
• Freight effect: heavier board raises pack weight 30–50% after conversion, so chargeable weight follows the carrier volumetric divisor of 5,000–6,000 cm³/kg.
• Ranges are typical industry values for the material or process named and are not a specification; confirm the exact value, the current edition of each standard and the applicable grade with your supplier or test laboratory.