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Paper Weight (GSM to lb) Calculator

Convert any gsm paper weight to the equivalent US text, cover, and bond pound ratings.

How it is calculated

The tool divides the weight in grams per square metre (gsm) by a fixed factor for each US paper category: text lb = gsm ÷ 1.48, cover lb = gsm ÷ 2.7048 and bond lb = gsm ÷ 3.7608. Each factor is the gsm value that corresponds to 1 lb of basis weight for that category's basic sheet size, so a heavier sheet gives a higher pound number. The three results are rounded to two decimals and shown in lb. Only a gsm value above zero is accepted. The pound figure is a nominal catalogue rating, not a measured weight, so mills often round it to a familiar value such as 80 lb.

Worked example

A brochure is printed on 120 gsm paper. Text basis weight = 120 ÷ 1.48 = 81.08 lb. Cover basis weight = 120 ÷ 2.7048 = 44.37 lb. Bond basis weight = 120 ÷ 3.7608 = 31.91 lb. The same sheet is therefore about "80 lb text", but only about "44 lb cover" and "32 lb bond".

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Common mistakes

  • Comparing pound numbers across categories. An "80 lb text" sheet is about 119 gsm, while "80 lb cover" is about 216 gsm, so these are very different thicknesses.
  • Using the wrong column for the job: look at the pound rating for the paper category your supplier lists (text, cover or bond), not the largest or smallest number.
  • Entering the pound value in the gsm box. The input is metric gsm only, and this tool does not convert pounds back to gsm.
  • Confusing weight with thickness. Two sheets with the same gsm can have different thickness (caliper) depending on coating and bulk.
  • Expecting an exact match with a catalogue. Suppliers round nominal values, so 81.08 lb may be listed as 80 lb.

About this calculator

This calculator converts metric gsm (grams per square meter) — a single, category-independent measure of paper density — into US basis weight in pounds, which is defined differently for each paper category because it's the weight of a ream (500 sheets) cut to that category's traditional “basic size”: 25×38 in for text/book paper, 20×26 in for cover stock, and 17×22 in for bond/writing paper. That's why the same gsm value produces a different pound number depending on whether you're converting for text, cover, or bond stock — the conversion factor isn't universal.

Graphic designers and print buyers use this to translate a European or Asian printer's gsm spec into the US pound ratings that American paper suppliers list, and print shops use it to make sure a client's requested “80 lb text” and “80 lb cover” — which are not the same actual thickness — are matched correctly to the job.

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