Overview
Lot tracking is essential for traceability, particularly in regulated industries or for products with expiration dates. However, when dealing with Fulfilled by Amazon (FBA), it’s important to understand that Amazon does not support or respect lot-level tracking. This document explains why that is, how Amazon handles inventory, and how Luminous reflects these processes for better visibility and control.
How Amazon Handles Inventory (and Ignores Lots)
When you send inventory to FBA, Amazon distributes it across multiple fulfillment centers—often automatically and without consideration of lot numbers.
Example:
Let’s say you send Lot 123A of SKU 1 with 60 units to Amazon.
Amazon might split this across:
Warehouse A: 10 units
Warehouse B: 10 units
Warehouse C: 10 units
Warehouse D: 10 units
Warehouse E: 10 units
Warehouse F: 10 units
If each warehouse sells unevenly (say A sells all 10, B sells 5, C sells 5, D sells all 10, and E/F sell none), when you send another lot (e.g., Lot 456B) later, Amazon will "replenish" each warehouse to even out inventory, again without respect to the lot.
🚨 Key Point: When a customer places an order, Amazon fulfills it from the nearest warehouse, regardless of lot. It does not prioritize older lots (FIFO) or return lot numbers on outbound shipments.
What This Means for Lot Tracking in FBA
Because of the above behavior:
FBA does not report back the lot number when items are sold.
When you create a transfer in Luminous to FBA using a lot, it will add to the total inventory, but Amazon will deplete stock based on internal logistics, not the lot.
This creates a scenario where inventory depletion appears lot-agnostic in your reports.
How Luminous Displays This
Let’s walk through a practical example:
Scenario:
You send 160 units of SKU 1, Lot 123A to FBA.
150 units of SKU 1 are sold within Amazon.
What You See in Luminous:
FBA Location Inventory:
Lot 123A: 160 units
Unspecified-lot: -150 units
What This Means:
Even though you sent 160 units of a known lot, Amazon doesn’t tell us which lot was used to fulfill the 150 units sold. Luminous reflects this by creating an “unspecified-lot” depletion entry. This can look confusing at first—but it’s the most accurate way to represent what actually happened in the system.
Tips for Users
Don’t expect lot-level traceability within Amazon once items enter FBA. If you need strict lot tracking, consider fulfilling via your own warehouse or a 3PL that supports it.
Use “unspecified-lot” entries in Luminous as indicators of what Amazon consumed, not what you sent.
If reconciling lot counts, always consider the original lot sent minus unspecified depletion to infer what remains.