Stock keeping units (SKUs)

In ecommerce, every product you sell exists across multiple touchpoints such as your website, marketplaces, ads, and fulfillment systems. Keeping all of this aligned depends on one simple but critical identifier: the SKU.

While shoppers never see it, the SKU ensures that the right product is listed, synced, and delivered accurately across every channel.

What is a stock keeping unit (SKU)?

A stock keeping unit (SKU) is a unique alphanumeric code assigned to a specific product to identify and track it within a business’s inventory and ecommerce systems.

Each SKU represents a distinct product variation, such as size, color, or configuration. For example, a black sneaker in size 42 will have a different SKU than the same sneaker in size 43. In ecommerce, SKUs don’t just track inventory; they connect product data across systems, ensuring accurate listings, pricing, and availability across channels.

How SKUs are structured

SKUs are typically designed using a logical format that reflects key product attributes, making them easier to interpret and manage. While the exact structure varies by industry, the goal remains consistent: create a format that is readable, scalable, and aligned with how your business manages products.

For example: Apparel SKUs often encode size and color, electronics SKUs focus on technical specifications, and FMCG SKUs prioritize simplicity and speed. For example: SNKR-BLK-42-001

This SKU might represent:

• Product type: SNKR (sneaker)
• Color: BLK (black)
• Size: 42
• Unique identifier: 001

A well-structured SKU helps teams quickly identify products, reduces errors in operations, and simplifies catalog management, especially when dealing with large product assortments and multiple variants.

SKUs vs. other identifiers

SKUs are often confused with other product identifiers, but they serve different purposes:

• SKUs (Stock Keeping Units)

Internal identifiers created by businesses to manage inventory, track product variations, and organize catalogs. SKUs are fully customizable and designed around how a company structures its products, making them essential for day-to-day operations like stock tracking, fulfillment, and reporting.

• GTINs / UPCs / EANs

Standardized global identifiers are used across retailers, marketplaces, and supply chains to uniquely identify products. These are assigned by manufacturers or governing bodies and are required by platforms like Amazon or Google to ensure consistent product recognition across different sellers and regions.

• Product IDs (platform-specific identifiers)

Unique identifiers generated by ecommerce platforms or marketplaces for individual listings or items. These IDs are used within specific systems (e.g., a marketplace listing ID or internal product ID in an ecommerce platform) and help manage products within that environment, but are not transferable across different platforms.

Unlike global identifiers, SKUs are fully customizable and tailored to internal operations.

Best practices for managing SKUs

To keep ecommerce operations efficient and scalable, SKU management should follow a consistent approach:

• Use a clear, logical structure: Encode key attributes like product type, color, or size to make SKUs readable
• Keep naming conventions consistent: Standardization ensures smooth data syncing across platforms and teams
• Ensure every variant has a unique SKU: Avoid duplication to prevent listing errors and fulfillment issues
• Plan for scale: Design SKU formats that can accommodate catalog growth and new product lines
• Align SKUs across systems: Keep SKUs consistent across your ecommerce platform, inventory system, and external channels to maintain data accuracy

SKUs may seem like a small detail, but they play a big role in how efficiently products are managed, sold, and delivered. As ecommerce grows more complex, with products distributed across multiple channels and platforms, having a clear and scalable SKU strategy becomes essential. In short, SKUs are not just inventory labels; they are the foundation of organized, scalable commerce operations.

See how you can simplify SKU management and scale across channels with Productsup. Book a demo with us today!