Plan replenishment before your sellable stock runs out. This calculator combines sales velocity with production, transit, receiving time, and a safety-stock buffer. It is useful for Amazon inventory, warehouse stock, or products sold through an independent store.
How to use this calculator
Enter average daily unit sales and the full time from placing a replenishment order to having sellable stock. Subtract units already committed to orders. If you have an inbound shipment, include the number of units and the days until it becomes sellable. Choose a planning date.
Formula and assumptions
Reorder point = daily sales × (lead time + receiving time + safety-stock days), rounded up. Current days of cover = available units ÷ daily sales. An inbound shipment extends continuous coverage only when it arrives before current available stock is exhausted.
Worked example
At 10 units per day, 25 days production/transit, five days receiving, and seven days safety stock, reorder point is 370 units. With 500 on hand and 20 committed, 480 units are available. Without inbound stock, current cover is 48 days and the reorder point is reached in 11 days.
Common questions
Why include receiving time?
A delivered carton may not yet be ready for sale. Receiving, inspection, and fulfillment-center processing belong in the time between ordering stock and being able to sell it.
Does this forecast seasonality?
No. It assumes constant daily sales and one inbound shipment. Run higher and lower sales scenarios for peak seasons, and review stock that arrives too late to prevent a gap. Dates are rounded to the earlier calendar day.
