Basis weight

Basis weight is a US-specific measurement indicating the weight of a ream, or 500 sheets, of paper at a standardized base size. Unlike GSM, which measures grams per square meter regardless of sheet dimensions, basis weight relies on category-specific base sizes. For example, text and book paper uses a 25 × 38 inch base, while cover stock uses 20 × 26 inches. Because the base size varies by paper type, a 100 lb text paper is physically thinner and lighter than a 100 lb cover paper.

This system allows printers and designers to quickly assess paper thickness and durability within a specific category. While international standards favor GSM for its absolute precision, basis weight remains the primary reference in North American print production. Understanding the distinction is crucial when converting specifications for business cards, where cover stock weights typically range from 14 to 16 points.