Safety Stock Calculator

Calculate safety stock

Safety stock is the buffer of extra inventory held to guard against running out when demand or supplier lead times are higher than expected. This calculator uses the common maximum method: safety stock equals maximum daily usage times maximum lead time, minus average daily usage times average lead time. It also computes the reorder point, the inventory level at which you should place a new order, which is the average lead-time demand plus the safety stock. These figures help you avoid stockouts without holding excessive, costly inventory.

The method captures both demand variability and supply variability, the two main causes of stockouts.

Balancing service and cost

Safety stock is a balancing act. Too little risks stockouts that lose sales and damage customer trust, while too much ties up cash and storage and risks obsolescence. By basing the buffer on how much usage and lead times actually vary, this approach sizes the cushion to the real risk rather than guessing. The reorder point then signals exactly when to reorder so that stock arrives before the buffer is needed.

For more precise control, statistical methods use the standard deviation of demand and a chosen service level, but the maximum method is a practical, widely used approximation. Review the inputs as demand and supplier performance change. All calculation happens locally in your browser.

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