SKU (Stock Keeping Unit)
A SKU (Stock Keeping Unit) is a unique alphanumeric identifier assigned to a specific product variant for inventory tracking and order management purposes.
What is a SKU?
A SKU, or Stock Keeping Unit, is a unique alphanumeric code assigned to a specific product variant to identify it within an inventory management system. Each distinct combination of product attributes — such as color, size, or configuration — gets its own SKU.
For example, a T-shirt might have the base product "Classic Tee," but if it comes in 3 colors and 4 sizes, that results in 12 individual SKUs, one for each unique variant.
SKU vs. Other Product Identifiers
- SKU — internal identifier assigned by the seller or retailer
- UPC/EAN/GTIN — universal identifiers recognized across all trading partners
- ASIN — Amazon's internal identifier for products in their catalog
- MPN (Manufacturer Part Number) — assigned by the manufacturer
Best Practices for SKU Design
Well-designed SKUs encode useful information in a structured format. For example, "TS-RED-M" might represent a T-Shirt in Red, Medium. Consistent SKU patterns make catalog management, inventory tracking, and reporting more efficient.
Frequently Asked Questions
How many SKUs is too many?
There is no absolute limit, but SKU proliferation — creating too many variants with very little sales volume each — can inflate inventory costs and complexity. Regular SKU rationalization reviews help identify underperforming variants.
Can two products have the same SKU?
No. A SKU must be unique within your catalog. Duplicate SKUs cause inventory mismatches, order errors, and reporting inaccuracies.