A backorder is an accepted order, or part of one, that remains unfulfilled because the item is unavailable for the required fulfillment. It may have an estimated replenishment date, or the date may still be unknown.
A supplier can backorder your purchase, and your business can accept a customer's backorder. A stockout describes unavailable stock; a backorder describes demand retained for later fulfillment. A stockout may instead result in a lost sale, cancellation or substitute.
Backorder versus partial shipment
A partial shipment supplies part of an order. The remaining quantity may be backordered, scheduled for a later delivery, disputed or canceled. Do not infer the status of the balance from the fact that one shipment arrived.
Keep these quantities distinct:
- Originally requested quantity.
- Supplier-accepted quantity and delivery schedule.
- Quantity physically received and accepted.
- Quantity still outstanding, including any disputed or canceled portion.
A changed ETA is a proposal or update to review, not evidence of delivery. The PO status tracking workflow is the relevant software evaluation when those facts are scattered across messages.
Worked example: the same 15-unit gap
In this fictional example, a retailer ordered 60 units and has already received 40. After subsequent sales, 30 usable units remain on hand. The outstanding 20 units are now expected 15 days from now. Assume demand is exactly three units per day, with no other stock, orders or commitments.
The 30 units cover ten days. The modeled shortage before the delayed receipt is therefore . The earlier 40-unit receipt is already reflected in current on-hand stock; do not add it again.