Kraft Paper Grammage (GSM): Concept, Meaning and How to Choose

Reviewed and updated by ICD - Week 24/2026

Key summary

Paper grammage is the weight of one square meter of paper (g/m²). It determines the thickness, stiffness and load capacity of kraft paper.

Common kraft paper grammages range from about 70 g/m² to over 450 g/m². Choosing the right grammage is the key to balancing performance and cost in packaging, while optimizing protection of goods from mechanical force.

1. What is kraft paper grammage?

Kraft paper grammage is a technical term for the mass of paper per unit area. The international standard unit is g/m² (grams per square meter).

For example:

• If kraft paper grammage is 80 g/m², a sheet of 1 square meter (1m x 1m) weighs 80 grams.
• If grammage is 300 g/m², that sheet weighs 300 grams per square meter, indicating much thicker, heavier paper.

Grammage is not just weight; it directly measures the material’s physical properties that give packaging its strength:

1. Thickness: higher grammage means thicker paper, which directly affects puncture resistance.
2. Stiffness: higher-grammage paper is stiffer and deforms less under pressure, helping a box hold its shape.
3. Load capacity: heavier paper usually withstands tensile, compression and tear forces better. This is a key metric for load-bearing applications.

2. Common kraft paper grammages and their applications

Kraft paper has a very wide grammage range, meeting almost every packaging need from consumer to heavy industry. Here is a detailed breakdown:

2.1. Low grammage (about 70-120 g/m²)

• Traits: thin, flexible, high elasticity.
• Applications:
  • Light food paper bags, single-use paper bags.
  • Gift wrap, anti-scratch lining paper.
  • Paper packaging requiring high elasticity at low cost.

2.2. Medium grammage (about 150-250 g/m²)

• Traits: moderate stiffness, balancing strength and economy. This is the most widely used grammage group.
• Applications:
  • Standard kraft paper bags and medium-load shopping bags.
  • The liner (facing) of E- and B-flute corrugated boxes.
  • The outer layer of Level 1-2 dunnage bags (usually laminated from several layers). It is also the material used to make kraft-paper dunnage bags.

2.3. High grammage (about 280-450 g/m²)

• Traits: thick, very stiff, with good compression and puncture resistance.
• Applications:
  • High-strength kraft cartons (3-ply, 5-ply).
  • Boxes for heavy products (electronics, machinery, bottles).
  • The liner for industrial cartons needing the highest compression strength.

2.4. Paperboard and industrial use (above 450 g/m²)

• Traits: very thick and stiff, used for industrial applications under heavy load and strong impact.
• Applications:
  • Cement bags, large industrial packaging, jumbo bags.
  • The liner of A- and C-flute boxes requiring maximum compression strength.

3. Choosing the optimal kraft paper grammage

Grammage affects both material cost and the quality and safety of goods in transit. For the best balance (highest performance at lowest cost), weigh these four factors:

3.1. Product weight, size and compression strength

This matters most. The heavier and larger the product, the higher the grammage needed so the box can bear the load and stacking force.

• Box Compression Test (BCT): a box’s compression strength is proportional to the grammage of the kraft liner used as the outer facing. Low grammage makes boxes deform or collapse when stacked in warehouses or containers.
• Rule of thumb: to add about 20% load capacity, you must raise the kraft paper grammage accordingly.

3.2. Transport mode and environmental risk

For goods shipped long distances, with multiple handling steps or stored in high humidity, the paper needs higher strength and stiffness.

• Moisture risk: kraft paper absorbs moisture. As humidity rises, paper strength drops significantly. So for international or sea transport, choose a grammage above the minimum.
• Moisture-proofing: consider PE-laminated kraft paper to create a vapor barrier. The laminate does not change the base grammage but protects it from moisture, preserving the inherent compression strength.

3.3. Printing and aesthetic requirements

Grammage also affects print quality and brand perception.

• Flexo printing quality: medium-to-high grammage (above 150 g/m²) usually has a flatter, less wavy surface, giving sharper flexo printing (common on cartons). Paper that is too thin can wrinkle or tear during printing.
• Brand cue: some brands deliberately choose a higher grammage than needed (for example a 200 g/m² bag for a light product) to feel premium and durable in the customer’s hands, reinforcing brand value.

3.4. Production process considerations

Grammage must suit the production equipment. Kraft paper that is too thick can hamper folding, cutting or corrugating machines, slowing the process and raising the defect rate.

4. Standards and control of kraft paper grammage

Grammage control is a key part of quality management. Grammage tolerance directly affects packaging cost and safety.

4.1. Test standards (ISO and TAPPI)

• ISO 536: the international standard for determining the grammage of paper and board. Testing cuts a sample of precise area (usually 100 cm²) and weighs it on a dedicated analytical balance.
• Allowed tolerance: in the paper industry, grammage tolerance is usually accepted within ±3% to ±5% of the stated grammage. Outside this range, packaging may fail to bear load or waste material cost.

4.2. Grammage and packaging cost

Grammage is proportional to the mass of paper used. So the higher the grammage, the higher the raw-material cost.

Cutting grammage too far to save cost can risk goods damage, causing far greater loss than the initial saving (re-manufacturing, shipping, insurance).

Packaging makers therefore always seek the optimal grammage - just enough to protect the product without waste.

5. Quick Q&A on kraft paper grammage

Q1: Is a higher kraft paper grammage always a better carton?

Not entirely. Higher grammage raises box compression strength so it bears load better. But unnecessarily high grammage wastes cost. The optimal grammage matters most: just enough to bear stacking force and protect goods in your specific supply chain.

Q2: Does grammage affect recyclability?

Yes. Higher grammage usually needs more energy to pulp. However, chemically, kraft paper (lightly bleached) is still one of the easiest papers to recycle, regardless of grammage.

Q3: Can 150 g/m² be used for dunnage bags?

A single layer of 150 g/m² is not enough. Container-load dunnage bags need a multi-layer structure. For example, a Level 1 bag may use 4-6 layers of 120-150 g/m² kraft pressed together, plus a moisture barrier, to reach 15,000 lbs compression.

Q4: How does paper weight differ from grammage?

Grammage is a material property (mass per square meter, g/m²), a fixed value for a paper type. Paper weight is the actual total mass of a roll or bale (in kg or tons). Grammage is the basis for calculating the total paper weight needed.