GSM: A Simpler System for Paper Weight

What’s thicker, 65# cover, 90# index, or 100# offset? It’s a question most print industry people know the answer to, but only after a fairly confusing learning period. GSM, g or g/m2 is a common term in European countries that’s gaining momentum here in the United States. These are the metric designations to indicate “grams per square meter” and quite simply, the bigger the number, the thicker the paper.

For reference, printing paper is generally between 60 and 150 GSM. 20# copy paper or 50# book paper is about 75 GSM. Anything heavier than 160 GSM is considered card/cover stock. Most digital equipment manufacturers specify minimum and maximum GSM for their paper capacity restrictions, and so more and more digital papers show GSM on their cartons or reams.

Micro Format Inc. has a fairly comprehensive paper weight conversion page at their website, along with international metric page sizes and other print/paper facts.