What is "safety stock"

n. (context management operations English) Additional inventory planned to buffer against the variability in supply and demand plans, that could otherwise result in inventory shortages.

Safety stock (also called buffer stock) is a term used by logisticians to describe a level of extra stock that is maintained to mitigate risk of stockouts (shortfall in raw material or packaging) due to uncertainties in supply and demand. Adequate safety stock levels permit business operations to proceed according to their plans. Safety stock is held when there is uncertainty in demand, supply, or manufacturing yield; it serves as an insurance against stockouts.

Safety stock is an additional quantity of an item held in the inventory in order to reduce the risk that the item will be out of stock, safety stock act as a buffer stock in case the sales are greater than planned and or the supplier is unable to deliver the additional units at the expected time.

With a new product, safety stock can be utilized as a strategic tool until the company can judge how accurate their forecast is after the first few years, especially when used with a material requirements planning worksheet. The less accurate the forecast, the more safety stock is required to ensure a given level of service. With a material requirements planning (MRP) worksheet a company can judge how much they will need to produce to meet their forecasted sales demand without relying on safety stock. However, a common strategy is to try and reduce the level of safety stock to help keep inventory costs low once the product demand becomes more predictable. This can be extremely important for companies with a smaller financial cushion or those trying to run on lean manufacturing, which is aimed towards eliminating waste throughout the production process.

The amount of safety stock an organization chooses to keep on hand can dramatically affect their business. Too much safety stock can result in high holding costs of inventory. In addition, products which are stored for too long a time can spoil, expire, or break during the warehousing process. Too little safety stock can result in lost sales and, thus, a higher rate of customer turnover. As a result, finding the right balance between too much and too little safety stock is essential.