A reorder-point policy places a new purchase order whenever on-hand stock drops to a threshold, sized to cover expected demand during the supplier's lead time.
ROP = demand_rate * lead_time + safety_stock
Stockout if Stock(t) < 0
HoldingCost = Σ stock(t) * unit_cost * rate
- Order (demand) rate — how many units customers pull off the shelf per simulated day; shown as boxes visibly leaving the shelf.
- Reorder point — the stock level that triggers a new incoming shipment; set it too low and you risk running out before the truck arrives.
- Lead time — how many simulated days a placed order takes to arrive; longer lead times need a higher reorder point to avoid stockouts.
Watch the instanced boxes on the shelf rise and fall with the stock-level bar as days tick by; a well-tuned reorder point keeps the shelf from ever hitting zero (a stockout, logged in red) while not holding so much stock that holding cost balloons.