Overview

Creating a properly formatted inventory file is one of the most fundamental tasks for Amazon sellers who manage their catalog through bulk uploads. This Seller Central reference page walks through the entire process of populating an inventory file template with your product data, from assigning SKUs and product identifiers to setting up variation relationships and configuring shipping lead times. Getting this right is essential for maintaining accurate listings and avoiding costly catalog errors.

Key Points / What Sellers Need to Know

• SKU is your most important field — Every product in your inventory file must have a unique SKU that cannot be altered or reused once created. Uploading data with an existing SKU will overwrite previous information.
• Product identifiers are strongly recommended — Always include a UPC, EAN, JAN, or ISBN when creating new product pages to ensure proper catalog matching and reduce listing errors.
• Search terms drive discoverability — You can assign up to five keyword fields per product to help customers find your listings through Amazon search.
• Parent-child relationships are mandatory when applicable — If a variation theme exists for your product category, you must set up parent-child relationships to group related items together.
• Lead time to ship directly affects customer messaging — The availability value you enter (0-30 days) determines what shipping estimate Amazon displays to buyers on your product page.
• Always save as tab-delimited text — Your completed inventory file must be saved in tab-delimited (.txt) format before uploading to Seller Central.

How SKUs Work in Amazon's Catalog

The SKU (Stock Keeping Unit) serves as the primary identifier linking your product listings to your individual inventory records in Amazon's catalog. Each new SKU you upload creates a brand-new record, and once established, that SKU persists until you explicitly delete it. This means sellers need to be deliberate about SKU assignment from the start, since changing a SKU later is not possible — you would need to delete the old one and create a new entry. If you upload an inventory file containing a SKU that already exists in your catalog, the most recent data will replace whatever was there before. For this reason, Amazon recommends keeping dated backup copies of your completed templates so you can reference prior versions if a processing error occurs.