GSM

GSM stands for grams per square meter and measures how much a fabric weighs relative to its area, which is a good proxy for how thick or dense it is. It is used across sheets, blankets, and quilts to describe weight independent of the fiber used.

Lower GSM fabrics are thinner and generally allow more airflow, which is why lightweight summer blankets and quilts are often labeled with a specific low GSM range. Higher GSM fabrics, like heavier flannel sheets or thick blankets, trap more heat and suit colder seasons or cold sleepers rather than someone trying to cool down.

A common mistake is comparing GSM numbers across different fiber types as if they behave identically. A low GSM synthetic fabric can still sleep warmer than a slightly heavier natural fiber because the material itself insulates differently. GSM is most useful for comparing two products in the same fabric family, such as two cotton blankets, rather than across completely different materials.