To the new print buyer there are certainly many confusing aspects to commercial printing. But there is one aspect that remains confusing even to the well seasoned print buyer. Paper weight.

Paper terminology starts out confusing even before we start to discuss weight. A few of the same words are used to describe both paper grade and paper type. Our three most common paper grades are Bond, Offset and Coated. These grades describe how a paper is manufactured.

Paper types are categorized by their intended use and are grouped together based on their Basis Weight which will be defined in the next paragraph. Common paper types include Bond (encompassing bond, writing, ledger and copier papers), Offset (also referred to as uncoated which includes offset, book and text papers), and Cover Weight. So from these two lists, we can see that there are crossover words. This is a problem because we can define a Coated Cover Weight or an Offset Cover but not a Coated Bond or Uncoated Writing stock.

Despite the grade and type issues outlined above, the true root of the paper weight problem is Basis Weight. This is defined as the weight of 500 sheets of a paper’s base parent sheet size. The catch is that each paper category has a different base sheet size. Bond papers (bond, writing, ledger and copier) have a base sheet size of 17″ x 22″. Offset papers (offset, book and text, both coated and uncoated) have a base size of 25″ x 38″. Cover stock (coated and uncoated) has a base size of 20″ x 26″. So a 80# Text weights nearly half that of an 80# Cover.

I’m sure you’re thinking that there must be a better way. There is. GSM or Grams per Square Meter. This is the weight of a single sheet of paper in grams that measures 1 meter by 1 meter square. There is no basis weight for different types or categories of paper – all paper is weighed in the same way. Paper type, finish, bulk, brightness and color still have to be defined just as it would with basis weight stock, but we can at least avoid having to use equivalency charts and confusing terminology to specify weight. Unfortunately GSM is rarely used in North America for offset printing. The one bright spot is that it seems to be catching on in digital printing and as this segment matures, it may provide the catalyst to finally embrace GSM – or at least an imperial version that only North America will use. Ounces per square fathom. Grains per square inch. Drams per square foot. Only time will tell.