Grammage

Grammage is a measure of the mass of a sheet of paper per unit area. It is expressed in grams per square meter (g/m^2) and is the standard metric for specifying paper weight in many regions, especially Europe. The term derives from the gram-based convention used in papermaking.

Grammage is determined by cutting a specimen of known area from a sheet, weighing it with a precision balance, and calculating mass per unit area. The official standard method is defined by ISO 536. In practice, mills and testing labs use grammage testers to obtain consistent results. Grammage is related to thickness (caliper) but they are not the same: two papers with identical grammage can differ in thickness due to density and fiber structure.

Common ranges reflect typical applications: office papers are about 70–100 g/m^2, text weights around 90–120 g/m^2, cover weights roughly 120–260 g/m^2, and card stock 200 g/m^2 and higher. In the United States, weight is often expressed as basis weight (pounds per 500 sheets of a specified standard size), which is a separate convention from grammage.

Grammage influences handling, opacity, stiffness, and durability. Higher grammage generally yields stronger, less translucent paper and is favored for cards, covers, and packaging, while lower grammage is common for everyday printing. It is a key parameter across printing, publishing, and product design, with considerations for recyclability and environmental impact depending on fiber content and production methods.