Ship Window / Delivery Window

A ship window is the range of dates during which a supplier must ship a purchase order; a delivery window is the range of dates during which the shipment must arrive at the retailer's facility. Together, they define the acceptable timeline for fulfilling an order and form the basis for on-time measurement in OTIF programs. Shipping before the window opens is as much a violation as shipping after it closes – early deliveries can disrupt a retailer's warehouse labor plan and inventory flow just as badly as late ones.

Ship and delivery windows are set by the retailer on each purchase order, often calculated backward from a promotional start date, shelf reset, or distribution center receiving schedule. A typical delivery window might be two days – for example, "deliver between March 10 and March 11" – while the corresponding ship window depends on the origin-to-destination transit time. Some retailers define only the delivery window and expect the supplier to calculate the appropriate ship date; others specify both.

Managing ship and delivery windows is straightforward for a handful of orders but becomes a serious planning challenge at scale. Each PO may have a different window, a different destination, and a different required transit time. Shippers must plan production, coordinate warehouse pickups, select carriers with the right service level, and monitor transit – all against overlapping and shifting windows across their entire order book.

The most common window violations are preventable: orders that sat in a queue too long before shipping, carriers booked without enough transit buffer, or shipments that went out on time but encountered an unmonitored delay in transit. Real-time visibility into where every shipment stands relative to its window – not just where it is on a map – is what turns window management from reactive to controlled.