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REORDER POINT SUBSYSTEM
In the EOQ model discussed we have made the assumption that the lead-time for procuring material is zero. Consequently, the reorder point for replenishment of stock occurs when the level of inventory drops down to zero. In view of instantaneous replenishment of stock the level of inventory jumps to the original level from zero level. In real life situations one never encounters a zero lead-time. There is always a time lag from the date of placing an order for material and the date on which materials are received. As a result the reorder level is always at a level higher than zero, and if the firm …ver más…

The question will naturally arise as to the magnitude of safety stock. There is no specific answer to this question.
However, it depends, inter alia, upon the degree of uncertainty surrounding the usage rate and lead-time. It is possible to a certain extent to quantify the values that usage rate and lead-time can take along with the corresponding chances of occurrence, known as probabilities. These probabilities can be ascertained based on previous experiences and/or the judgmental ability of astute executives. Based on the above values and estimates of stock-out costs and carrying costs of inventory it is possible to work out the total cost associated with different levels of safety stock.
Once we realize that the higher the quantity of safety stock, the lower will be the stock-out cost and the higher will be the incidence of carrying costs, the formula for estimating the reorder level will call for a trade-off between stock-out costs and carrying costs. The reorder level will then become one at which the total stock-out costs (to be more precise, the expected stock-out costs) and the carrying costs will be at its minimum.

REORDER POINT FORMULA
Even in a relatively simple situation considered in the example above, the amount of calculations involved for arriving at the