Tools you might need next
Calculate book spine width from page count, paper weight, and binding type. Free book spine width calculator for self-publishing and print layout design.
Calculate print bleed, trim size, and safe margins for offset and digital printing. Set artwork dimensions for full-bleed brochures and business cards.
Calculate printing cost per page from toner, paper, and maintenance expenses. Free print cost per page calculator for office budgets and self-publishing.
GSM (g/m²) is the mass of one square meter of paper regardless of sheet size. It is the international standard and the most direct comparison between stocks.
GSM = Paper mass (g) / Area (m²)US bond weight is lb per 500 sheets of 17×22 inch (basis ream). Convert to GSM: multiply bond weight by 1.48 for text/bond basis. Example: 20 lb bond ≈ 75 GSM.
GSM ≈ Bond weight (lb) × 1.48Cover stock uses 20×26 inch basis; index uses 25.5×30.5 inch. Each basis size yields a different lb number for the same physical thickness. Always note which basis system is used.
GSM ≈ Cover weight (lb) × 2.704; Index ≈ lb × 1.875Updated: July 2026
Standard US copy paper at 20 lb bond converts to approximately 75 GSM. Specify 75 GSM when ordering equivalent stock from European suppliers.
100 lb cover stock (20×26 basis) converts to roughly 270 GSM — a heavy cardstock suitable for business cards and postcards with good rigidity.
300 GSM premium card stock converts to approximately 110 lb cover. Useful when a printer quotes GSM but your local supplier lists cover weights.
100 lb cover is much heavier than 100 lb bond because cover uses a smaller basis sheet. Always convert both to GSM before comparing.
Within one basis system, higher weight means heavier paper per area. But coated stocks can be denser — a 80 lb text coated sheet may be thinner caliper than 70 lb uncoated offset.
Paper is sold under different weight systems — GSM (grams per square meter), bond basis weight (lb/500 sheets), cover weight, and index weight. The same physical thickness can have different numbers depending on the basis size. This converter translates between systems so you can specify stock correctly.