SKU

What is a SKU?

A SKU is a short code you create to identify one specific product variant and follow it through stock, sales, and shipping. Each version of a product, such as a size, color, or model, gets its own code.

Businesses rely on SKUs because a single store can carry a huge range of goods, and product names alone cause mix-ups. To see the scale, note the average supermarket item count: on average, supermarkets carry 33,248 items in the store in 2025 (FMI). A good inventory control system leans on unique codes to prevent stockouts, speed up picking, and keep records accurate.

Unlike a universal product code (UPC) or European article number (EAN), which retailers share across the whole market, a SKU is yours to define however you like. That is why two companies can stock the same item under completely different codes.

The same code follows an item everywhere it appears, from an online product listing to a warehouse bin label to the receipt at checkout. That shared reference lets sales, purchasing, and shipping teams point to the exact same product without second-guessing which one they mean.

Key characteristics

A few traits set SKUs apart from other product codes. These attributes are what make them useful for everyday operations.

• Internal and customizable: Each business sets its own SKU format because there is no universal standard. That freedom lets you encode the details your team cares about most.
• Alphanumeric and readable: SKUs mix letters and numbers so people can read them at a glance. Short, clear codes cut down on typing errors at the shelf.
• One per variant: Every size, color, and model combination gets its own code. This keeps similar products from being confused during picking and counting.
• Attribute-encoded: Segments usually move from broad to specific, such as product type, then brand, then size, then color. Teams building and formatting codes often follow a guide for using SKU numbers so the pattern stays consistent.
• Powers reporting: SKU-level data feeds turnover, profit, and reorder analysis. That detail helps you spot which items sell and which ones tie up cash.

Some simple habits keep a SKU system healthy. Avoid baking the selling price into a code, keep segments in the same order for every product, and leave the format stable as the catalog grows.

Researchers have measured the payoff of clean SKU data. A 11% sales lift from audits came from a field study of about 24,000 SKUs across 11 stores, where an inventory audit led to an 11% store-wide sales lift (Rekik et al., 2026).

Example

Take a power-tool seller listing an 18V cordless drill. It assigns DR-18V-COR-BLK to the black model and a separate SKU to each other color, so pickers grab the exact variant every time.

An apparel seller works the same way with a lightweight denim jacket. It codes the black medium as LJ-BLK-M and the black large as LJ-BLK-L, so the warehouse never ships the wrong size to a customer.

Good codes also make reordering faster. When each variant has its own SKU, a low count triggers a purchase order for that one item, not a guess about which size or color is running short. Vague or reused codes do the opposite and let a hot seller sit empty while a slow one piles up.

Poor SKU discipline carries a real cost. The $1.7 trillion inventory distortion figure shows the stakes; the 2026 measurement puts the annual worldwide cost at $1.7 trillion, equal to 6.2% of global retail sales (IHL Group, 2026). Tight inventory habits lower that risk: oil-and-gas firm Extract Production reported 22% fewer stockouts after adding AI-driven forecasting with Fishbowl.

The screenshot shows Fishbowl’s SKU management best practices.

Related terms

• UPC tracking system shows how scannable barcodes differ from internal SKUs.
• inventory reporting turns SKU data into turnover analysis.
• no-excuse SKU basics covers the fundamentals of setting up codes from scratch.

FAQ

How is a SKU different from a UPC? A SKU is an internal code you create and control, while a UPC is a standardized barcode used across every retailer. Two companies can assign the same product different SKUs.

How do you pronounce SKU? Most people say it as one word, “skew,” rather than spelling out the letters.

How long should a SKU be? There is no fixed rule, but most codes run about 6 to 12 characters. Keep them short and readable, and avoid easily confused characters like “0” and “O.”