Use the Basis Weight Calculator to convert between GSM (g/m²) and U.S. basis weight (lb per 500-sheet ream) for common paper grades (basis sizes). You can also estimate sheet/ream weights for a custom sheet size and calculate roll weight by length or by roll diameters.

Basis Weight Calculator

Convert paper GSM to pounds (or vice versa) for any standard grade.

GSM ↔ lb
Sheet Weight
GSM → lb
lb → GSM
g/m²
▸ How this is calculated
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Basis Weight Formula

The following example problem outlines the steps and information needed to calculate the basis weight (lb per 500-sheet ream) from GSM and the grade’s basis size.

BW = \frac{GSM \times A_{basis} \times 500}{453.59237}

Variables:

  • BW is the U.S. basis weight in pounds (lb) for a 500-sheet ream at the stated basis size
  • GSM is the grammage in grams per square meter (g/m²)
  • Abasis is the area of one sheet at the basis size (m²)

To calculate the basis weight in lb, multiply the GSM by the total area of 500 basis-size sheets (in m²) to get grams per ream, then divide by 453.59237 to convert grams to pounds.

How to Calculate Basis Weight?

The following steps outline how to calculate the basis weight (lb per 500-sheet ream) from GSM.

  1. First, determine the paper grade (basis size) or enter a custom basis sheet width and height.
  2. Next, determine the grammage in GSM (g/m²).
  3. Next, compute the basis sheet area Abasis in m² (for inches, 1 in² = 0.00064516 m²).
  4. Next, calculate grams per ream: grams = GSM × Abasis × 500.
  5. Finally, convert grams to pounds: BW = grams ÷ 453.59237.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Paper grade (basis size) = Bond/Writing (17×22 in)

GSM (g/m²) = 80

BW = (GSM × Abasis × 500) / 453.59237 = ?