SKU
Also: Stock Keeping Unit, SKUs, Lagereinheit, Lager-Einheit, Lagerhaltungseinheit
AI-generated
A SKU (Stock Keeping Unit) is a unique alphanumeric identifier that unambiguously identifies an item in a specific variant — such as color, size, or packaging unit.
Key facts
- A SKU uniquely identifies an item in a specific feature variant and is the smallest manageable unit in a warehouse system.
- The granularity of the SKU structure directly influences the complexity of planning, inventory management, and picking.
- Internal SKUs do not need to match manufacturer article numbers or EAN codes — they follow the company's own process requirements.
- Too many active SKUs increase storage costs and planning effort — regular SKU rationalization is a proven method for inventory optimization.
What is a SKU?
SKU stands for Stock Keeping Unit and refers to the smallest unit that is managed independently within a warehouse or inventory management system. Each SKU represents a unique combination of an item and its inventory-relevant features — typically color, size, material, or packaging type. Two products that differ in even one of these features are assigned separate SKUs. This enables precise stock allocation, seamless tracking of goods movements, and accurate control of replenishment processes.
How does a SKU work in practice?
In day-to-day operations, the SKU links physical warehouse stock with digital records in the ERP or WMS. During goods receipt, every delivered unit is assigned to a SKU; storage location, stock quantity, and movement history are all managed under this identifier. During picking, the SKU determines which item in which variant is to be picked — whether manually via barcode scan or automatically through a conveyor system.
The granularity of the SKU structure has a direct impact on operational processes:
- SKUs that are defined too granularly significantly increase complexity in planning and warehouse management.
- SKUs that are defined too broadly lead to mix-ups and mispicks.
- The optimal level of granularity depends on the business model, channel structure, and system capabilities.
In practice, many companies also distinguish between internal SKUs and manufacturer article numbers or EAN codes. The internal SKU follows the company's own warehousing and process requirements, while external identifiers are used for communication with suppliers and trading partners.
What matters when designing SKUs?
Several factors need to be considered when introducing or revising a SKU system. First, the SKU logic should be built consistently and transparently — for example, following a defined schema based on product category, variant, and sequential number — so that it remains manageable even during system migrations or when onboarding new employees.
Second, the number of active SKUs has a direct impact on storage costs, minimum order quantities, and the complexity of ABC analyses. Regular SKU rationalization — the targeted phase-out of variants with low turnover rates — is an established part of inventory management in many operations.
Third, accurate master data maintenance is critical: incorrectly or duplicately created SKUs are a common cause of inventory discrepancies and picking errors. System-side validation rules and clearly defined responsibilities for master data management help prevent such issues.
Related terms
- ABC-Analyse
ABC analysis is a method for classifying items, vendors, or processes into three priority classes (A, B, C) based on their economic significance. It forms the basis for differentiated decision-making in warehousing, inventory management, and procurement.
- Artikel
An item is the smallest uniquely identifiable unit in warehousing, procurement, and ERP – described by master data such as name, dimensions, weight, and identification numbers. It forms the basis for planning, order picking, and inventory management.
- Artikelbezeichnung
The item description is the human-readable name of an item in the inventory management or warehouse management system. It helps people in purchasing, logistics, and planning to quickly identify an item and distinguish it from others.
- Artikeleinheit
The item unit defines the unit of measure in which an item is managed, posted, and handled within the system. It forms the basis for consistent inventory management, picking, and pricing.
- Artikelklassifizierung
Item classification refers to the systematic categorization of items based on defined criteria such as value, turnover frequency, storage requirements, or hazardous material characteristics. It forms the foundation for differentiated warehousing, procurement, and picking processes.
- Artikelnummer
The item number is an internally assigned, unique identifier that unambiguously identifies an article within the inventory management and warehouse system. It forms the basis for postings, purchase orders, and communication between purchasing, warehousing, and production.
- Artikelstamm
The item master is the central data repository that permanently stores all logistically and commercially relevant features of an item. It forms the basis for warehousing, inventory planning, picking, and billing.
- Artikelstammdaten
Item master data refers to the permanently valid base data of an item – such as dimensions, weight, packaging units, hazardous goods classification, and best-before date relevance. It forms the foundation for all logistical, procurement-related, and system-driven processes along the supply chain.
- Barcode
A barcode is a machine-readable optical code that represents information as a pattern of bars and spaces or as a two-dimensional matrix. It enables the automatic identification of items, load carriers, and documents along the entire supply chain.
- Bestandsführung
Inventory management refers to the system-supported administration and continuous updating of all warehouse and material stocks within a company. It forms the basis for planning, procurement and accounting – and ensures that the book inventory and physical inventory are in agreement at all times.
- Bestandsmanagement
Inventory management refers to the systematic planning, control, and monitoring of stock levels across the entire supply chain. The goal is to ensure delivery capability while keeping capital commitment and warehousing costs within economically viable limits.
- Charge
A batch is a uniquely identifiable quantity of products manufactured or processed under identical conditions. It forms the basis for traceability, quality control, and legally required recall processes throughout the entire supply chain.