What is a SKU? What is a barcode? What is an Alternative Code? Why are they important?

What is a SKU? What is a barcode? What is an Alternative Code? Why are they important?

Overview

To manage your products effectively across different sales channels and fulfilment partners, it’s essential to understand the role of SKUs and Alternative Codes. This article explains what they are, how to use them, and best practices for setting them up in the Bezos Seller Portal.

1. What is a SKU?

A SKU (Stock Keeping Unit) is a unique identifier you assign to each product and product variation in your catalogue. SKUs are used internally to:
  1. Track inventory
  2. Manage warehouse operations
  3. Ensure accurate order fulfilment (prevent mispicks)
  4. Analyse product performance
Example: A medium black t-shirt might be labelled: TSH-BLK-M
Note: SKUs are created by you and should be meaningful to your business and operations.

2. SKU vs Barcode vs UPC vs EAN

It’s common to confuse SKUs with barcodes and other identifiers. Here's how they differ:

IdentifierCreated ByPurposeCustomisableUsed Across Channels
SKUYouInternal tracking & operations✅ Yes❌ No
General barcodeGS1 or system-generatedMachine-readable for scanning❌ No✅ Yes
UPC barcodeGS1North American barcode (12 digits)❌ No✅ Yes
EAN barcodeGS1European barcode (13 digits)❌ No✅ Yes

SKUs are for internal reference, while barcodes are for scanning in retail and logistics environments. It is very important that your products have a physical barcode on the product, ideally a UPC or EAN barcode.

3. What is an Alternative Code?

In multi-channel environments, a product might be referred to by different identifiers across systems like Amazon, Shopify, or wholesale portals. Alternative Codes (also called Alt Codes) bridge this gap.

Definition: An Alternative Code is a secondary product reference used to link external systems or marketplace listings to your internal SKU.

These mappings ensure orders are always linked to the correct stock, regardless of where the order originates.

4. How to Create SKU Numbers (Best Practices)

When creating SKUs, follow these four principles:
  1. Keep it meaningful
    1. Include only important product details: type, colour, size, etc.
    2. Example: TSH-BLK-M = T-shirt / Black / Medium
  2. Be consistent
    1. Use a standard format across your catalogue.
    2. Example: [Category]-[Colour]-[Size]
  3. Be unique
    1. Every product and variation should have its own SKU. Avoid duplicates.
  4. Avoid confusing characters
    1. Don’t use special characters, spaces, or lookalikes (e.g. O vs 0). Use hyphens or underscores instead.

5. Aligning SKUs Across Sales Channels

Depending on how you operate, you can align SKUs in two main ways:

Option 1: Use the same SKU across all platforms (recommended)
  1. Simplifies inventory syncing
  2. Ideal for smaller catalogues or when platforms allow it
Option 2: Use Alternative Codes in the Bezos Seller Portal
  1. Ideal when external platforms use different product codes
  2. Bezos links these to your main SKU so that order routing, inventory updates, and fulfilment remain accurate
💡 To set up Alternative Codes in Bezos, go to the product’s details page and add alternative codes. More information in this Help Center article.

Summary

SKUs and Alternative Codes are essential for accurate inventory and order management. Especially when selling across multiple channels. By setting up a clear SKU structure and linking external identifiers using Alt Codes, you’ll streamline your operations and reduce fulfilment errors. UPC and EAN barcodes on your products are essential for ensuring that the right product gets picked for your orders.

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