Calculate laminate GSM layer by layer

The purchasing question

A laminate is not one homogeneous film. Each substrate has its own thickness and density, and dry adhesive or coatings remain in the finished web. Omitting these additions understates purchased mass and overstates square metres available per kilogram.

Calculation method

Calculate each substrate contribution as thickness in µm × density in g/cm³. Add the substrate GSM values and the dry coat weights of the adhesive interfaces, ink and coatings that are not already included in the measured substrate figures. Use measured total GSM as a check when available.

Worked example

Assume a 12 µm layer at 1.40 g/cm³ and a 50 µm layer at 0.92 g/cm³. Their contributions are 16.8 and 46 GSM. Adding 2.5 GSM of dry adhesive gives 65.3 GSM total. A 10,000 m² order contains an estimated 653 kg, including 25 kg of dry adhesive.

These are illustrative properties, not a recommended material specification. The estimate excludes any coating not entered. At 65.3 GSM, yield is approximately 15.3139 m²/kg; using only the substrates would incorrectly predict 15.9236 m²/kg.

Checks before using the result

• List every substrate and adhesive interface.
• Use dry retained coat weight in the finished laminate.
• Avoid adding coatings again when already included in measured GSM.

Common questions