The level of safety stock does not depend on the cost to reorder stock.
Safety stock is held in order to avoid the likelihood of a stock out, or running out of inventory. A higher level of safety stock is needed when sales forecasts are uncertain. Customers dislike waiting for orders to be filled, and lead time from suppliers is uncertain.
The cost of reordering inventory is a consideration in the optimal quantity of inventory to order each time an order is placed, but not in the additional safety stock that should be held. When the inventory falls to the level of minimum safety stock, then a new order should be placed.
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