ISO 534:2005 specifies two methods for measuring the thickness of paper and board:
a) the measurement of a single sheet of paper or board, as a single sheet thickness,
b) the measurement of a pack of sheets of paper as a bulking thickness.
It also specifies the following calculation methods, from the thickness determinations:
calculation methods for the apparent sheet density and for the apparent bulk density;
calculation methods for the apparent specific sheet volume and for the apparent specific bulk volume.
It is not applicable to corrugated fibreboard, and method a) is not applicable to materials with a grammage higher than 225 g/m2.