gramatur

Gramatur, also known as grammage or grammatura in some languages, is a measure of the mass per unit area of a sheet material. It expresses how heavy or dense a material is for a given area, typically in grams per square meter (g/m^2), abbreviated gsm. The concept is widely used for papers and textiles, and it also applies to other sheet materials such as plastics and cardboard.

Measurement and standardization: A sample with a defined area is weighed with a precise balance. The gramatur is calculated as mass divided by area. For paper, standardized methods such as ISO 536 specify testing conditions and sample preparation; for textiles, methods are similar but often use per-square-meter area as the basis. Humidity, moisture content, and finishing can influence the measured value, so testing conditions are standardized to ensure comparability.

Interpretation and use: Gramatur allows comparison of materials independent of sheet size. Higher gramatur generally indicates a heavier, thicker, or stiffer material, though density and composition also affect the feel and performance. In paper, gramatur influences opacity, rigidity, and print quality. In textiles, fabric weight affects drape, warmth, and durability, and different finishing processes can alter the effective gramatur.

Typical ranges: Paper used for office printing typically falls around 70–120 gsm, while art or cover papers may range from 160–300 gsm; packaging boards can reach 300 gsm or higher. Fabrics show broad variation: lightweight fabrics around 40–120 g/m^2, medium-weight 120–250 g/m^2, and heavy fabrics above 250 g/m^2. Values vary by material, production method, and standard used.