M&K Print Resources · Free calculator
GSM to LB Paper Weight Converter
Compare paper weights in either direction. Choose the paper category so the pounds mean the right thing.
Decimals are welcome.
Your result
Enter a weight and select a category.
Two ways to describe paper weight
GSM measures mass in grams per square meter. It stays consistent across paper categories. US pound weight describes the weight of 500 sheets at a category’s standard basis size.
Weight is only part of the picture
Weight alone does not determine thickness, opacity, finish or suitability for your book. Paper composition and coating also matter. Ask for samples when comparing stocks.
Paper weight conversion reference
Approximate values, rounded to one decimal place. Every basis weight uses 500 sheets.
| Category | Basis size (inches) | US basis weight | Equivalent GSM |
|---|---|---|---|
| Text / Book / Offset | 25 × 38 | 80 lb | ≈ 118.4 GSM |
| Cover | 20 × 26 | 80 lb | ≈ 216.3 GSM |
| Bond / Writing | 17 × 22 | 20 lb | ≈ 75.2 GSM |
| Bristol | 22.5 × 28.5 | 80 lb | ≈ 175.4 GSM |
| Index | 25.5 × 30.5 | 80 lb | ≈ 144.6 GSM |
Common paper questions
What does GSM mean?
GSM means grams per square meter. A square meter of 120 GSM paper has a mass of 120 grams.
Why is 80 lb text different from 80 lb cover?
Text uses a 25 × 38 inch basis sheet, while cover uses 20 × 26 inches. An 80 lb text stock is about 118.4 GSM; an 80 lb cover stock is about 216.3 GSM. Always include the category with a pound weight.
Can I convert GSM to paper thickness?
Not reliably. Stocks with the same GSM can have different thicknesses. Check the manufacturer’s caliper specification or ask for a sample rather than treating weight as thickness.
How is the conversion calculated?
GSM = lb × 453.59237 ÷ (500 × basis width × basis height × 0.0254²). The reverse calculation converts GSM to pounds. Width and height are in inches; calculations use full precision before rounding.
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