Reinforced concrete structures in marine environments are susceptible to various degradation mechanisms that significantly impact their durability. Steel reinforcement corrosion caused by chloride ingress is a major concern. Extending the service life of these structures often involves improving their resistance to chloride penetration, which translates to lower chloride diffusion coefficients. Unfortunately, obtaining these coefficients through traditional methods is time-consuming. This study addresses this limitation by comparing long-term diffusion testing, with an accelerated method, a chloride migration test. We investigate the influence of water-to-cement ratio (w/c), cement content, exposure duration, and chloride concentration on the correlation between chloride diffusion coefficients obtained from the field and migration coefficients derived from the accelerated method (NT Build 492). The results indicate that diffusion and migration coefficients exhibit a stronger correlation with increased cement content and shorter exposure durations. Consequently, the accelerated migration test can be a reliable alternative to the time-consuming traditional diffusion test under these conditions. However, the correlation weakens as chloride concentration and exposure period increase. This finding highlights the significant influence of mix design and exposure conditions on the correlation between chloride diffusion and migration coefficient.