Paper Weight Converter (GSM ↔ lb)

Convert paper weight for packaging and printing. Select paper type and enter a value to convert instantly.

Basis sizes and formulas shown below — frontend only, no sign-in required.
Result
0.287 lb
Approximate basis weight for Cover paper.
Basis size: 20 × 26 in (Cover paper)
Valid GSM range: 40–600 (typical packaging values)

GSM vs lb: Understanding Paper Weight

GSM (grams per square meter) and pound (lb) basis weight are two common ways to describe paper weight. In packaging and printing, GSM is widely used globally, while lb is commonly used in North America.

Why GSM matters for packaging

  • Controls stiffness and durability of carton boxes and labels.
  • Helps printers estimate shipping weight and material costs.
  • Chooses appropriate board for folding cartons, cosmetic boxes, and rigid covers.

How the conversion works

The tool uses industry formulas to convert between GSM and lb based on the paper basis size (the sheet dimensions used to define pound weight). The core formula used (frontend-only) is:

lb = (GSM × sheet_area_in_square_inches × 0.00220462) / 1000

And the inverse used is:

GSM = (lb × 1000) / (sheet_area_in_square_inches × 0.00220462)

Comments in the code explain the rationale and constants used.

Common paper weights in packaging

  • 250 GSM — Folding carton (boxes)
  • 300 GSM — Cosmetic box stock
  • 350 GSM — Rigid cover board
  • 120 GSM — Label and sticker papers

FAQ

What is GSM in paper?

GSM is the mass of paper in grams per square meter. It describes how heavy or thick the paper feels.

How do you convert GSM to pounds?

Use the conversion above and select the correct basis size for the paper type. This tool does the math instantly for you.

Which paper weight is best for carton boxes?

Folding cartons commonly use 200–350 GSM depending on required strength and finishing. Cosmetic or luxury boxes often use 300–350 GSM.

Is GSM the same worldwide?

GSM is an international metric standard. The pound (lb) basis weight depends on regional basis sizes, so conversion requires the basis size.