Estimating coastal sediment budgets presents significant challenges due to the complex nature of coastline configurations and the often-bimodal wave regime. This study investigates longshore sediment transport (LST) along the Gulf of Cadiz by analyzing estimates obtained from various wave data sources and employing various approaches. The sensitivity of transport calculations to different wave data sources and approaches is evaluated, and the impact of easterly waves, or “Levante,” is examined for the different approaches. The nearshore wave regime was simulated using the SWAN model, with offshore conditions from ERA5 hindcast and the Faro buoy. Results were validated using observational data and LST was estimated using a deep water approximation of the CERC formula, extracting the net transport and the two components of the sediment transport: west-east and east-west. The results emphasize the critical importance of selecting appropriate forcing for applied models to simulate the nearshore wave regime and estimate sediment transport.