Wetting dynamics plays a central role in applications such as coating processes, microfluidics, and green energy technologies. Despite extensive theoretical work, several aspects of the influence of droplet size on wetting dynamics still elude us, such as how nanoscale dynamics manifest at macroscales as the sys- tem size grows. In this contribution, we present a detailed molecular dynamics study of droplet wetting on silica surfaces, focusing on the role of surface wettability and system size effects on macroscopic scaling laws. Initially spherical droplets of varying radii are placed in contact with silica substrates and are simulated to capture their spreading behaviours. The substrate wettability is tuned by introducing hydroxyl ions at different concentrations, yielding equilibrium contact angles spanning the hydrophilic regime, namely from 0◦ to ∼ 90◦ .The surface ion number density (C ≈ 0–9.4 nm−2 ) was varied at the silica–water interface. Complete wetting (contact angle 0°) was observed at C ≈ 4.7 nm−2 . For each case, the temporal evolution of the droplet is analysed in detail, recovering equilibria which are consistent with spherical cap geometries. At early times, we observe the well-established t 1/2 power law for neck formation, whereas at later times the system transitions toward the viscous-dominated spreading regime characterized by a t 1/10 scaling, which emerges provided that the system under consideration is sufficiently large. Our results demonstrate how the dynamics and scaling laws observed at macroscopic scales are modu- lated by finite system size effects. They provide quantitative guidelines for designing simulations across length scales and contribute to a systematic multiscale framework for describing wetting phenomena.