What the reorder point tells you
The reorder point (ROP) is the inventory quantity at which a new purchase or production order should be triggered, so that stock does not run out before the new order arrives. It is calculated as: ROP = (average daily usage × lead time in days) + safety stock.
How this calculator works
Enter your average daily usage (how many units are sold or consumed per day), your supplier’s lead time (how many days it takes for a new order to arrive), and your safety stock (an extra buffer to cover demand spikes or delivery delays). The calculator multiplies usage by lead time to get expected demand during the resupply window, then adds the safety stock on top.
- When on-hand inventory drops to this level, it’s time to reorder.
- Increasing safety stock reduces stockout risk but ties up more capital in inventory.
This tool is for general inventory planning purposes and assumes fairly steady, predictable demand and lead times.
Last reviewed August 2026