The total lead time cost is the sum of extra carrying cost (ECC) and stock out cost
(SOC). From the table above, known that the optimal lead time for 2012 is 7 days, this is
because the total cost is the lowest compared to others, which is IDR 22,809,436/year. With
the same way, the result of the optimal lead time calculation based on EOQ model with total
minimum cost from 2007-2012 are: