In the metric system, the density of all types of paper and paperboard is expressed in terms of grams per square meter (g/m²). This quantity is commonly called grammage. In countries that use United States paper sizes, a less direct measure known as basis weight is used in addition to or instead of grammage. So how do you tell a 300gsm sheet from an 80lb cover? Here's the best online paper weight converter we've seen.

Last updated on August 5, 2011 by Joshua Levine