This paper examines alternative metods of inventory calculation and the calculation of inventory cost for M SAN d.d. company. The goal of the paper is to show core features of alternative methods of cost calculation and to run and compare financial effects for different methods of cost calculation. The theoretical part of the paper elaborates in more detail the notion of inventory, type, division, purpose and accounting inventory monitoring. The second part of the theoretical discussion describes the inventory calculation using the average weighted cost method and the FIFO method used for external reporting purposes as well as alternative inventory accounting methods (LIFO Methods, HIFO Methods, NIFO Methods and Fixed Cost Methods) used only in internal reporting. Alternative methods of cost calculation are based on a different way of recording the costs of spent inventories, which was the aim of the research. The empirical study describes the company M SAN PLC, their activity, financial report, and the way of managing and calculating inventories. By analyzing the company, it was established that the method of average weighted procurement costs was used to calculate inventory consumption. Further analysis was conducted to investigate the method of average weighted costs for the most profitable enterprise, applying inventory of all alternative methods for Kingston SD 32GB. In the period of one month, the results of the calculation of inventories of alternative methods were compared with the average cost method and an additional FIFO method and the method of average weighted costs was compared to 17 different items. The results obtained confirm that the method of average weighted costs is more cost-effective than the FIFO method and other alternative methods of inventory calculation. The conclusion confirms the hypothesis set and summarizes the overall research.