In print production, a key paper parameter is its weight, measured in grams per square meter (gsm). It is always listed in manufacturer catalogs. However, many mistakenly equate weight with caliper. That is fundamentally wrong: weight is mass, not thickness.
With designer papers, a lighter sheet is often thicker than a heavier one because of bulkier fibers. Think of a brick and a pillow: the brick weighs more, but the pillow is thicker.
The higher the weight, the more caliper can vary between sheets with similar gsm values. Paper at 90 gsm will most likely be thinner than 150 gsm. But 260 gsm paper may end up thicker than, or similar in thickness to, 300 gsm. Hopefully I have not confused you even more.
