Soft granular materials, consisting of highly deformable disordered particles, find applications in various industrial sectors such as pharmaceuticals, cosmetics, food, and powder metallurgy. These materials are often shaped under confinement stresses in processes like extrusion or compaction, resulting in tablets or compacts with a microstructure resembling that of porous media. The compaction stage remains challenging to describe, marked by changes in particle shape, volume, and rearrangements within the grain bed. In this context, suitable numerical models are necessary to capture the significant deformations of particles at the contact level. An important challenge lies in ensuring the representativity of simulated systems for industrial applications. The number of simulated particles relative to the system size is a key parameter. In tis presentation we will focus specifically on the finite size effects of systems composed of slightly polydisperse elastic spherical particles confined within rigid cylinders of varying diameters. These particles will undergo quasi-static uniaxial compression with a home-made code relying on couple approaches based both on material point method for bulk particle deformations and contact dynamics method to address particle-particle interactions. The diameter and height of the cylinders will be vary based on the number of particles, allowing us to elucidate how the number of particle influences important packing parameters such as stress transmission, solid fraction, or connectivity.