The ISO 534 standard specifies methods for determining the thickness, density and specific volume of paper and Cardboard. The standard helps to evaluate the physical properties of paper and Cardboard through precise experimental methods, ensuring that the product meets mass requirements. Thickness is determined by compressive measurement of paper or Cardboard samples using appropriate instruments, and density is obtained by calculating the mass in a unit volume, which is the volume size per unit mass. These physical properties are important for the production, use and quality control of paper and Cardboard. The standard provides methods for determining the mass conformity of paper products and promoting their Reliability in different applications.