What Is a SKU? Complete Guide to Stock Keeping Units

A stock keeping unit (SKU) is a business-created identifier for a specific inventory item or product variant. A company assigns its own SKUs, so there is no universal SKU registry or required format. The same product can have different SKUs at different businesses.

What does SKU mean?

SKU stands for stock keeping unit. It can describe the distinct item being tracked or the internal code attached to it. A T-shirt in three sizes and two colors normally creates six SKUs because each variation is counted, sold, and reordered separately.

The SKU links a product to its inventory record. That record can hold the name, variant, category, supplier, cost, price, stock, location, barcode, reorder point, and transaction history. The code does not contain all this information; software uses it to find the correct record.

How SKUs work

Every stock movement should reference the intended SKU. Receiving increases its quantity, a sale decreases it, and a transfer moves quantity between locations. Returns, damage, waste, and count corrections also update the SKU through distinct stock actions.

1. Create one record for each separately stocked item.
2. Assign an SKU unique within the business's catalog.
3. Store UPCs, EANs, supplier codes, and barcode values in their own fields.
4. Use the same SKU across purchasing, receiving, POS, counts, transfers, and reporting.
5. Do not change a live SKU without mapping historical records and integrations.

SKU example and anatomy

Consider COF-BEA-ETH-1KG:

This is an example, not a standard. Another business could use ETH-BEAN-1000 or CF-0142. The goal is consistency, internal uniqueness, system compatibility, and enough readability to prevent mistakes.

What makes a good SKU?

• Unique: one active SKU identifies one stock record.
• Stable: exclude price, temporary location, and other changing details.
• Readable: make similar items easy to distinguish.
• Consistent: control segment order, abbreviations, separators, and case.
• Variant-specific: distinguish size, color, flavor, material, and pack quantity.
• Practical: keep it short enough to type, print, and support across connected systems.

How to create an SKU system

1. Define the stock unit

Create a separate SKU whenever an item must be counted, purchased, sold, or reordered independently. A single bottle and a case of 12 may need distinct SKUs if both are transacted as separate units.

2. Choose stable attributes

Useful segments include category, product family, brand, model, material, color, size, flavor, and pack quantity. Put price, cost, stock, shelf location, and current supplier in separate fields.

3. Control abbreviations

Use one list so BLUE does not become BL, BLU, and BLUE. Avoid confusing characters such as O and 0 or I and 1 when staff type or read codes aloud.

4. Use a predictable structure

For example, apply category-product-variant-size throughout the catalog. Add an explicit sequence to resolve collisions instead of appending random characters.

5. Validate before import

Check duplicates, blanks, spaces, repeated separators, unsupported characters, excessive length, missing variants, and conflicts with current records. Test sample products across every connected system.

Build a consistent format with the free Stash SKU and variant generator. It creates internal SKUs; it does not issue official UPCs or EANs.

Do variants need different SKUs?

Usually, yes. Every separately stocked variant should have its own SKU. A mug with two sizes and three colors creates six inventory records. Sharing one SKU makes it impossible to know which exact variant sold, which is low, or what should be reordered.

For POS catalog structure, see Square items, variations, SKUs, and categories.

SKU vs. UPC, EAN, barcode, and serial number

Can an SKU be a barcode?

An SKU is not inherently a barcode, but its value can be encoded in one. Businesses often encode alphanumeric SKUs in Code 128 for internal receiving, counts, picking, transfers, or checkout. This does not turn the SKU into a registered UPC or EAN. Read the complete barcode guide for format selection.

Common SKU mistakes

• One SKU for several sizes, colors, or packs
• Reusing a retired SKU for a different product
• Encoding changing prices, suppliers, or locations
• Inconsistent abbreviations between people or locations
• Duplicate SKUs introduced by imports
• Changing live SKUs without updating connected records
• Assuming an SKU is globally unique or officially registered

How SKUs support inventory management

Clean SKUs make item-level counting, receiving, sales, purchase orders, reporting, reorder points, and transfers possible. The code alone does not create accuracy: every movement still needs the correct product, unit, quantity, and location. Regular cycle counts and controlled receiving keep records aligned with physical stock.

Frequently asked questions

What is an SKU?

An internal identifier for a specific product or variant in a business's inventory system.

Is an SKU the same as a barcode?

No. An SKU identifies a record; a barcode is a machine-readable way to encode a value.

Is an SKU the same as a UPC?

No. The business creates an SKU. A UPC is part of the standardized GS1 identification system.

Do I need to buy SKUs?

No. Businesses create their own. Official GTINs, UPCs, and EANs follow separate GS1 processes.

How long should an SKU be?

There is no universal length. Use the shortest format that remains clear, unique, and compatible.

Can SKUs contain letters and numbers?

Yes. Alphanumeric SKUs are common.

Should every variant have a different SKU?

Yes, when each variant is stocked, sold, counted, or reordered separately.

Can two businesses use the same SKU?

Yes. SKUs only need to be unique within each company's catalog.

Should an SKU change when price changes?

No. Price is a separate field and can change without changing product identity.

How do I turn an SKU into a label?

Encode it in a compatible format such as Code 128, print it, and test it with the real scanner and software. Use the free Stash barcode generator.

Build a reliable product catalog

Start with the free SKU generator, then create labels with the free barcode generator. For ongoing stock, purchasing, suppliers, forecasting, and multiple locations, explore Stash inventory management.

Sources and standards

• GS1: Global Trade Item Number
• GS1 barcode standards
• GS1 US guide to UPCs

Last reviewed: August 9, 2026.