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Print Publishing Paper Weight Converter

Convert paper weight between GSM, bond basis weight, cover stock, and index weight. Compare text, cover, and cardstock for print and packaging.

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Inputs that matter
Value, Conversion
Output to expect
Paper Weight Converter
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

GSM Definition

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)

Bond Basis Weight Conversion

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) × 1.48

Cover and Index Basis

Cover 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 × 1.875

Updated: July 2026

Example Scenarios

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.

Common Mistakes to Avoid

Comparing bond weight directly to cover weight numbers

100 lb cover is much heavier than 100 lb bond because cover uses a smaller basis sheet. Always convert both to GSM before comparing.

Assuming higher lb always means thicker paper within the same basis

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.

FAQ

In US printing, bond and text basis use the same 17×22 inch ream size, so 20 lb bond and 20 lb text are equivalent at approximately 75 GSM. Cover weight uses a different basis size and is not comparable by number alone.

Basis weight systems measure lb per 500 sheets of a specific parent sheet size. Larger basis sizes spread the same mass over more area, producing a higher lb number for identical thickness.

Standard US copy paper is 20 lb bond, approximately 75 GSM. Heavier letterhead might be 24 lb bond (~90 GSM). International A4 equivalent is typically 80 GSM.

Business cards typically use 300–350 GSM (roughly 110–130 lb cover) or 14–16 pt caliper. Weight alone does not indicate stiffness — fiber content and finish also matter.

No. Weight measures mass per area; caliper measures thickness in points or mils. Two stocks at the same GSM can differ in thickness depending on coating, fiber, and pressing.

About Print Publishing Paper Weight Converter

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.