How To Design SKU Codes For Your eCommerce Catalog

SKU A Stock Keeping Unit, an internal identifier used by a merchant to distinguish and track a specific sellable item. Designing SKU codes deliberately reduces picking errors, simplifies reporting, and enables accurate integrations between ecommerce, WMS, and accounting systems.

Good SKU design balances readability, system constraints, and longevity. Poorly designed SKUs force frequent renaming, complicate reporting, and raise error rates on the warehouse floor. The following guide lays out practical rules and examples to create SKUs that serve operations for years.

Core Design Principles

• Meaningful But Compact: Encode essential attributes (category, color, size) but avoid overly verbose strings that are hard to read or print.
• Stable Components: Use fields that rarely change (brand, category) and avoid attributes that can change frequently (price, promotional label).
• Consistent Format: Standardize order, separators, and character cases so humans and systems parse SKUs predictably.
• Avoid Ambiguous Characters: Exclude characters that confuse scanners or handwriting (spaces, slashes, symbols like # and %).

Practical Field Choices

Decide which product attributes are operationally important to encode in the SKU. Typical fields include:

• Category Code: Short code for major product family (e.g., TS for T-shirts, MUG for mugs).
• Brand/Manufacturer Code: Two–three character brand shorthand where multiple brands are handled.
• Variant Attributes: Size, color, material codes (S, M, L; BLK, WHT).
• Pack/Unit Count: When pack size matters: 6P = pack of six.

Example Formats

Here are three example SKU patterns and when to use them:

• Fixed Field: BR-CAT-MDL-COL-SIZ (e.g., NX-TS-123-BLK-M). Best where quick visual parsing by position is needed.
• Short Hybrid: CAT-BR-MDL-SIZ (e.g., TS-NX-123-M). Balances brevity and meaning for ecommerce catalogs.
• Sequence-Based: CAT-000123 (e.g., TS-000123) with attribute metadata stored in the product record. Best where system-driven lookups are primary and SKU brevity is desired.

Barcode And System Constraints

Ensure SKU characters are supported by all systems (WMS, ERP, ecommerce) and barcode fonts if SKUs will be directly encoded in barcode labels. Many barcode scanners and label printers handle alphanumeric codes, but certain legacy systems accept only numeric strings. When in doubt, coordinate with IT and label vendors before finalizing format.

• Character Sets: Prefer A–Z and 0–9; use hyphens or underscores sparingly.
• Length: Keep SKUs under 20 characters where possible — shorter is faster to type and scan.
• Leading Zeros: Decide if numeric fields require leading zeros and enforce them consistently.

Migration And Change Management

Changing SKU schemas after launch is costly. When redesigning SKUs, plan a migration that keeps historical data usable. Strategies include maintaining an alias table where old SKUs map to new SKUs and deploying the new SKUs in stages (new SKUs for new products, legacy for existing inventory) until stock is cycled.

• Alias Mapping: Store old→new SKU relationships in the product master for reporting and reconciliation.
• Integration Updates: Update ERP, WMS, marketplaces, shipping, and accounting integrations to consume the new SKU format concurrently.

Operational Tips

• Document The Schema: Publish a SKU style guide with examples and rules so new hires and partners follow the pattern.
• Automate Generation: Use your product information system or WMS to auto-generate SKUs to avoid human error during listing.
• Include Humans In Design: Test SKU readability with pickers and receiving staff — human factors matter under pressure.

In short, the SKU should be a stable, compact code that captures the operational attributes you need to find, pick, and report on items. Plan the schema, document it, automate where possible, and map legacy codes to preserve data continuity.