Reorder Point Calculator

The Reorder Point Calculator answers a single operational question: at what on-hand inventory level should you trigger a new purchase order so stock doesn't run out before the replacement arrives? Reorder Point is Lead Time Demand -- how many units you'll sell while waiting for the next shipment -- plus a Safety Stock buffer for demand that runs hotter than average. Lead Time Demand is simply Average Daily Demand multiplied by Lead Time, so raising either the demand rate or the supplier's lead time raises the reorder point in the same direction. Safety Stock, when you leave the override at 0, is calculated automatically from the Demand Std Deviation and a service-level Z-score -- a statistics shorthand for how much cushion you need to hit a target in-stock rate.

Raising Demand Std Deviation raises the calculated Safety Stock, because more variable demand means a bigger buffer is needed to avoid stockouts at the same confidence level; it does not, however, change Lead Time Demand itself, which only tracks the average, not the spread. If you enter a manual Safety Stock override greater than zero, it replaces the calculated buffer entirely. What this does not account for: supplier lead-time variability (only the average lead time is used), order batching or minimum order quantities, or multiple SKUs sharing warehouse capacity.