The ISO 1 2625-3: 2014 standard provides test methods for the determination of thickness, expansion thickness, apparent bulk density and volume of tissue and tissue paper products. The standard specifies measurement procedures at specific pressures (2.0 kPa) to ensure accuracy and conformity of results. It covers measurements of single-layer thickness, single-sheet thickness, expansion thickness, and apparent bulk density and volume calculated based on these data. The updated version of the standard revises the relevant requirements for Measurement accuracy and specimen prepative, further optimizing test methods. By providing a uniform measurement standard, ISO 1 2625-3 aims to enhance quality control and comparative analysis in the paper products industry.