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How Amazon Keeps Track of Your FBA Inventory

  • Ecommerce
  • December 10, 2015 | Marcus DeHart

Amazon loves numbers. Some numbers are relatively simple to figure out, such as units sold, units refunded, A-to-Z claims resolved, and shipped product sales. Other numbers involve elusive algorithms that Amazon keeps locked away to prevent sellers from gaming the system. You’ll be hard pressed to find a formula that calculates who wins the Buy Box or how the new product ratings are weighted. Many of these numbers are important to evaluate and improve performance so you (and Amazon) can have a successful online retail business.

Other numbers perform a very different function. It’s hard to pin down some of the most recent data, but in 2013, Amazon reported selling 426 items per second leading up to Christmas. In 2014, Jeff Bezos reported that Amazon added 30 million customers in the previous year for a total of 244 million.

At last count, they have a web presence in 13 countries and serve customers from 75 countries around the world. While those numbers alone are impressive, what’s truly amazing is the ability to track each item sold, every customer’s transactions, and every order shipped. All that is accomplished with numbers. Tracking numbers, to be specific (well, sometimes those tracking numbers are alphanumeric, but you get the picture).

If you use Fulfillment by Amazon (FBA), there are a few numbers that are especially important for tracking your inventory.

Inbound Shipments

Sending your inventory to Amazon can be like placing your child on a school bus for the first time. You know they’ll be in good hands, but it’s hard to let them go. With the school bus, you’ll most likely take note of the number and route of the bus. You’ll keep an eye on the schedule so you’ll know what time your child will arrive at school.

Amazon has numbers to help you track your inventory to their fulfillment centers. The shipment name is for your own use, so you can customize it using any naming convention you like or use Amazon’s default -- the date and time of the shipment's creation in Seller Central.

If you need to inquire about the status of the shipment, you’ll need, at the very least, the Shipment ID, which is an alphanumeric number that can be found in your shipping queue, on the shipment summary, and on your shipment label. If you are using a trucking company to ship inventory, you’ll want to make sure that the carrier has the Amazon Reference ID, which is only available on the shipment summary.

These numbers are critical to getting your inventory to Amazon, scanned, and sorted for storage. Each number will be associated with the contents of the boxes, and when the boxes are opened, each unit will be scanned and tallied against the list of products you provided when you created your shipment in Seller Central. Having an accurate count of your products and only including what you listed will prevent headaches that come with miscounts and unknown SKUs.

Inventory Storage

If you are labeling your own inventory or paying Amazon to do it, there is one number you need to be mindful of when tracking your inventory in storage. Amazon uses a fulfillment network SKU (FNSKU) to identify every labeled product that enters their facilities. This number is unique to each product and each seller.

So if you sell the same book that 10 other sellers offer on Amazon, your FNSKU will be unique to the books you send to Amazon. The 10 other sellers will also have unique numbers for their inventory. When Amazon unpacks your shipment, they scan each unit’s barcode and assign the product to a shelf in their warehouse. No other products go on that shelf with yours.

If you are sending stickerless, commingled inventory to Amazon, your product won’t have a label on it, so there’s no physical barcode or number that identifies the FNSKU. Amazon scans the UPC, ISBN, or other product identifier and assigns it to its own shelf. Note that even though these are commingled, they are not stored on the same shelf as other products or in a bin. Commingling happens when a customer places an order that is more easily fulfilled by using another seller's identical product.

Order Fulfillment

Order fulfillment is tracked using the Order ID assigned by Amazon. With the Order ID, you can identify the order status, destination, delivery timing, products purchased, quantities, and prices. You can find all this information by going to the Order menu and selecting 'Manage Orders.' Click on a specific Order ID to get your details. If you know the Order ID, you can use the search function to locate it.

Inventory Reports

Keeping track of all this information can be daunting if you have a large number of products. I’ll leave you with one report that will help audit your inventory at Amazon. The Inventory Reconciliation Report can be used to look up specific products by FNSKU or Merchant SKU. It gives you a summary of product disposition for a given time period. You get a breakdown of incoming (received, returned, etc.) and outgoing (sold, removed, lost, damaged, and disposed) units. All these numbers enable you to audit inventory at Amazon and get a better understanding of where your inventory is at any given time.


Avalara Author
Marcus DeHart
Avalara Author Marcus DeHart