Measured by weighing a known area of conditioned sheets, grammage is the international way to state how heavy a paper is. Opacity rises with it, and scattering and absorption coefficients cannot be calculated without it. Values run from under 30 g/m2 for bible paper and tissue to 150 g/m2 and more for heavy text and cover stock.
Grammage is running 1.5 grams light on the front edge, so opacity will be low there too.
Also heard as
- gsm
- g/m2
- substance
Do not mix it up with
- Basis weight: Basis weight is the North American ream figure in pounds, which depends on the basic sheet size of each grade.
Related terms
Basis weight
Weight of a 500-sheet ream cut to a grade's basic sheet size, used in North American paper trade.
Opacity
A sheet's ability to hide what lies behind it, expressed as a percentage from readings over black and white backings.
Caliper
Thickness of a single sheet of paper, measured under a set pressure and given in micrometers or thousandths of an inch.
Bulk
Volume per unit mass of paper, the inverse of density, usually given in cubic centimeters per gram.