This research focuses on the supply planning of a petrol station network with variable demand. It should be noted that analyzing demand behavior is crucial to make a forecast as close as possible to the actual demand through the most appropriate forecasting method. In this study, the 28-day demand was analyzed. Subsequently, an inventory model is developed to calculate the optimal order quantity (Q*) at each service station (petrol station) during the period. This model unites the characteristics of the continuous (Q, R) and periodic (P) review models. The Q* are the quantities needed to plan the supply, both the inventory and the number of transport units required to supply from the distribution centre to each petrol station. The number of transport units requires specific considerations, such as the minimum and maximum capacity of each vehicle, the freight costs, and the Q* of the stations. The objective is to minimize operating costs. In the fuel industry, inventory control is a regulatory requirement, so compliance not only avoids penalties but also ensures transparent and responsible business practices. Optimizing transport resources is crucial to improve operational efficiency, reduce costs, maximize customer satisfaction, and reduce pollutants in any logistics and distribution company, which also contributes to sustainability. This research shows a 63% reduction in network operating costs.