If you have ever bought paper for a printer or business card, you have met gsm, lb, caliper, and micron. These measure different things.
GSM: Grams per Square Metre
GSM (g/m²) is the metric standard. It measures the mass of one square metre of paper. Office paper: 80 gsm. Business card: 300 gsm. Poster: 250 gsm.
LB: Pounds per Ream
The US and UK use lb (pounds per ream of 500 sheets). The catch: the "basis size" matters. 20 lb US and 80 gsm are roughly equivalent.
Common GSM Values
- 35–50 gsm — newspaper
- 60–75 gsm — cheaper books
- 80–90 gsm — office paper
- 100–130 gsm — brochures
- 150–200 gsm — posters
- 250–350 gsm — business cards
- 350–450 gsm — packaging
Caliper: Thickness in Microns
Caliper is measured in microns (µm) or "thou" (thousandths of an inch). Caliper matters when folding thick paper.
Choosing the Right Weight
- Everyday printing — 80 gsm
- Newsletters — 100–130 gsm
- Posters — 150–200 gsm
- Business cards — 300–400 gsm