This International Standard 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. This International Standard also specifies calculation methods — for the apparent sheet density and for the apparent bulk density, and — for the apparent specific sheet volume and for the apparent specific bulk volume from the thickness determinations. This International Standard is not applicable to corrugated fibreboard. In addition, the measurement of bulking thickness, method b) above, is not suitable for board1). NOTE The two methods generally lead to different results. These methods are not applicable to tissue paper and tissue products. For tissue paper and tissue products, ISO 12625-3 should be used.