A clear SKU system gives every product and variant a consistent internal identifier. Instead of relying on long product names, memory, or different naming conventions across systems, your team can use the same code in purchasing, receiving, inventory, sales, and ecommerce.
For example, a black T-shirt in size M and the same T-shirt in size L may look like one product family, but they are different inventory items if they are purchased, counted, sold, or replenished separately.
In this guide, you will learn how to create SKU numbers, choose a practical naming structure, decide which product attributes to include, avoid common mistakes, and maintain your SKUs in a master product catalog.
You can also download the free SKU Generator & Master Catalog Excel Template used in the examples.
Quick answer: A SKU, or Stock Keeping Unit, is an internal identifier created by your business for a product or product variant. A practical SKU system keeps each code unique, follows a consistent structure, uses only stable product attributes, and avoids information that changes frequently, such as price, current stock, discounts, or temporary suppliers.
Table of Contents
- What Is a SKU and Why Does Your Business Need One?
- SKU vs. UPC, GTIN, Barcode, Lot Number, and Serial Number
- What Makes a Good SKU System?
- Before Creating SKUs: Decide What You Need to Track
- How to Create SKU Numbers Step by Step
- SKU Examples for Different Businesses
- What Should You Include in a SKU?
- How to Build a Master SKU Catalog
- How to Use SKUs Across Your Business
- Common SKU Mistakes
- SKU System Checklist
- Frequently Asked Questions About SKUs
- Free SKU Generator & Master Catalog Excel Template
What is a SKU and why does your business need one?
SKU stands for Stock Keeping Unit. In practice, it is an internal code your business uses to identify a product or product variant that it purchases, sells, stores, replenishes, or analyzes.
Suppose you sell the same basic T-shirt in black and white, with sizes M and L. From a marketing perspective, these items may belong to one product model. From an inventory perspective, however, each combination may need to be tracked separately.
| Product Variant | Example SKU |
|---|---|
| Black T-shirt, size M | APP-TSH-BLK-M-014 |
| Black T-shirt, size L | APP-TSH-BLK-L-015 |
| White T-shirt, size M | APP-TSH-WHT-M-016 |
A clear SKU system can help reduce problems such as:
- Recording the same product under different names
- Selling or shipping the wrong size, color, or pack size
- Receiving a different variant from the one ordered
- Mixing products with different costs or selling prices
- Not knowing which specific variant is running out of stock
- Using one internal reference in a physical store and another in ecommerce
- Making product-level reporting harder than necessary
A SKU does not replace inventory counts, receiving controls, or transaction records. It creates a common identifier so different parts of the business can refer to the same item consistently.
SKU vs. UPC, GTIN, barcode, lot number, and serial number
These identifiers are often confused, but they do not serve the same purpose.
| Identifier | Main Purpose | Who Defines It? |
|---|---|---|
| SKU | Identify and manage a product or variant inside a business | Your business |
| GTIN | Provide a standardized trade-item identifier used between organizations | Assigned within the GS1 identification system |
| UPC | A GTIN-12 commonly used for retail identification in North America | Based on the GS1 identification system |
| Barcode | Provide a machine-readable representation that can be scanned | Depends on the identifier and system being represented |
| Lot Number | Track a batch of production, purchasing, or inventory | Manufacturer or business |
| Serial Number | Identify one individual physical unit | Manufacturer or business |
The same item can therefore have several identifiers associated with it. Your business might use an internal SKU for inventory management, a GTIN represented in a barcode for commercial identification, and a lot number for traceability.
The important distinction is this: your SKU is primarily an internal operating identifier. It does not become a standardized UPC or GTIN simply because you print it as a barcode.
What makes a good SKU system?
A useful SKU system does not need to encode every detail about a product. It needs to make identification consistent enough for the people and systems that use it.
A practical system should generally be:
- Unique: each separately managed product or variant has its own SKU.
- Consistent: the same coding rules are applied throughout the catalog.
- Readable: employees can interpret the structure without decoding an unnecessarily long string.
- Stable: the SKU does not need to change every time price, stock, supplier, or location changes.
- Scalable: the structure can accommodate new products and variants as the catalog grows.
Sequential SKUs
A sequential SKU identifies an item without describing its characteristics.
Example: 0001847
This approach can work well when employees always use a product-information system to look up the item and do not need to interpret the code itself.
Structured or meaningful SKUs
A structured SKU contains short segments that represent selected product attributes.
Example: APP-TSH-BLK-M-014
| Segment | Meaning |
|---|---|
| APP | Category: Apparel |
| TSH | Product Type: T-Shirt |
| BLK | Color: Black |
| M | Size: Medium |
| 014 | Unique sequence |
Someone familiar with the coding rules can recognize the type of item directly from the SKU. This can be useful when a small business works with spreadsheets, manually receives merchandise, picks products from shelves, or operates across several sales channels.
Hybrid SKUs
A hybrid SKU combines a small number of stable product attributes with a unique sequence.
For many small businesses, this creates a practical balance between readability and uniqueness without turning the SKU into a complete product description.
The template in this guide uses that approach:
CAT-TYPE-VAR1-VAR2-001
Not every business needs every segment. The structure should fit the catalog rather than forcing every product into an unnecessarily rigid format.
Before creating SKUs: decide what you need to track
Do not begin by inventing abbreviations. First determine which products and variants your operation actually manages independently.
Ask these questions:
- Which products are purchased separately?
- Which variants are sold separately?
- Which variants have independent inventory?
- Which differences affect replenishment?
- Which attributes must employees recognize quickly?
- Which information changes frequently and should stay outside the SKU?
A useful practical rule is:
If a product or variant is purchased, sold, counted, replenished, or analyzed separately, it should normally have its own SKU.
For example, a black T-shirt in size M and the same T-shirt in size L should normally have different SKUs if you maintain separate inventory for each size. The same principle applies to products with different colors, flavors, materials, capacities, or pack sizes.
How to create SKU numbers step by step
The following example uses the same structure as the Excel template:
Category → Product Type → Variant 1 → Variant 2 → Sequence
Step 1. Define the category code
Start with a short code that groups similar products.
| Category | Example Code |
|---|---|
| Apparel | APP |
| Beauty | BEA |
| Hardware | HDW |
| Food | FOD |
| Home | HOM |
| Accessories | ACC |
You do not need dozens of categories just because the system allows them. Use categories that help organize the catalog and support purchasing, inventory, sales, or reporting.
Step 2. Define the product type code
After the category, add a short code for the product type.
| Product Type | Example Code |
|---|---|
| T-Shirt | TSH |
| Jeans | JNS |
| Jacket | JKT |
| Cap | CAP |
| Bag | BAG |
For example, APP-TSH already indicates a T-shirt within the Apparel category.
Step 3. Add only the variants that matter
Include an attribute when it helps distinguish a product or variant that your business manages separately.
- Color
- Size
- Flavor
- Material
- Capacity
- Pack size
- Measurement
For the apparel example:
APP-TSH-BLK-M
Here, BLK represents Black and M represents Medium.
Do not add attributes that do not create a useful distinction. A SKU with too many segments becomes difficult to read, enter, and maintain.
Step 4. Add a unique sequence
The sequence helps keep the complete SKU unique, even when several products have similar coded attributes.
The final example becomes:
APP-TSH-BLK-M-014
The number does not need to represent purchase date, cost, selling price, or current stock. Its purpose in this structure is simply to support uniqueness.
The Excel template accepts sequences from 1 to 999 and displays them using three digits, so sequence 14 appears as 014.
Step 5. Document your coding rules
Before creating hundreds of SKUs, document the codes your team should use. Otherwise, the same attribute may be represented in several different ways.
| Attribute | Code |
|---|---|
| Black | BLK |
| White | WHT |
| Blue | BLU |
| Brown | BRN |
| Medium | M |
| Large | L |
| One Size | OS |
| Pack of 12 | P12 |
Without a documented rule, one employee might enter Black as BLK, another as BLA, and another as BLACK. That inconsistency makes product searches, imports, reporting, and duplicate detection more difficult.
The workbook converts code segments to uppercase automatically, but your organization should still maintain one approved meaning for each code.
SKU examples for different businesses
The following examples show how the same logic can be adapted to different types of catalogs.
| Business | Product | Example SKU |
|---|---|---|
| Apparel store | Black T-shirt, size M | APP-TSH-BLK-M-014 |
| Beauty store | Argan shampoo, 400 mL | BEA-SHM-ARG-400-022 |
| Hardware store | 2-inch steel screw | HDW-SCR-STL-2IN-118 |
| Gourmet store | Whole-bean coffee, 500 g | FOD-COF-WHB-500-031 |
| Home store | 12-pack white towels | HOM-TWL-WHT-P12-009 |
| Restaurant | Hot sauce, 250 mL | FOD-SAU-HOT-250-043 |
Not every SKU needs the same number of segments. A business that sells products without variants may need only category, product type, and sequence. Another business may need color and size because those variants are counted separately.
What should you include in a SKU?
A structured SKU should contain enough information to help identify the item without trying to become a complete product record.
Information that may be useful in a SKU
- Category
- Product type
- Color
- Size
- Pack size
- Capacity
- Flavor
- Material
- Measurement
- Unique sequence
You do not need to include all of these fields. Select only the attributes that are stable and operationally useful.
Information you should usually keep outside the SKU
- Selling price
- Unit cost
- Current inventory quantity
- Warehouse or shelf location
- Purchase date
- Current discount
- Inventory status
- Lot number
- Expiration date
- Temporary supplier
These values can change while the underlying product remains the same. Embedding them in the SKU may force you to create new codes unnecessarily and can reduce historical consistency.
How to build a master SKU catalog
Creating codes is only the first part of the system. You also need a master catalog where each SKU is connected to the information employees need to buy, sell, replenish, and analyze the item.
A basic master catalog can contain fields such as:
| Field | Purpose |
|---|---|
| SKU | Unique internal identifier |
| Product Name | Clear description employees recognize |
| Category | Commercial or operational grouping |
| Product Type | Type of item within the category |
| Variant | Color, size, flavor, material, or other differentiator |
| Unit / Pack Size | How the product is purchased or sold |
| Unit Cost | Input for gross-margin analysis |
| Selling Price | Current selling value |
| Primary Supplier | Reference for purchasing and replenishment |
| Barcode / GTIN | Optional standardized or scannable product identifier |
| Status | Active, Draft, or Discontinued |
| Notes | Operational context that should not be embedded in the SKU |
The SKU should remain the identifier. Cost, price, supplier, barcode information, and status belong in separate fields because they can change without changing the identity of the product.
One important rule is to avoid reusing the SKU of a discontinued product. Even after the product stops selling, that SKU may still appear in historical purchases, inventory adjustments, sales, returns, and profitability reports.
How to use SKUs across your business
The value of a SKU system increases when the same identifier follows the product through the main operating processes.
Purchasing
Include the SKU in purchase orders so the requested variant is clear. Instead of relying only on a description such as “black medium T-shirt,” the order can identify APP-TSH-BLK-M-014.
Receiving
When receiving goods, verify that the SKU received matches the SKU ordered. Compare the product, variant, quantity, pack size, and condition before adding accepted units to inventory.
Inventory counts
Count and adjust inventory by SKU, not only by product name. Recording “10 black T-shirts” is not enough if six units are size M and four are size L and each size must be replenished independently.
Sales, ecommerce, and POS
Where your systems allow it, use the same internal SKU in your physical store, ecommerce platform, POS, and marketplaces. This reduces the risk that different channels use different internal references for the same item.
The product name presented to customers can change for marketing or merchandising purposes without requiring the internal SKU to change.
Reporting and profitability
When each relevant variant has its own SKU, you can analyze sales, margin, inventory movement, and slow-moving items at a more useful level.
If excess inventory is tying up cash in the business, our guide to working capital explains how inventory, receivables, cash, and short-term obligations affect liquidity.
Common SKU mistakes
Making SKUs too long
A SKU should be useful, not a technical product specification. Too many segments make codes harder to enter, read, remember, and maintain.
Embedding price or cost
Prices and costs change. A SKU should normally remain stable when a product goes on promotion, supplier costs increase, or the selling price changes.
Using different SKUs for the same inventory item
If purchasing calls a product one SKU while ecommerce or inventory uses another, reconciliation becomes harder. Maintain one master reference whenever the systems involved permit it.
Failing to create separate SKUs for variants
If color, size, flavor, material, or pack size is purchased, counted, sold, or replenished independently, combining several variants under one SKU can hide real inventory differences.
Using inconsistent abbreviations
Do not let each employee invent a different abbreviation for the same attribute. Document the accepted codes before the catalog becomes large.
Including spaces or extra separators inside code segments
Characters that are not part of your defined structure can make manual entry, imports, integrations, and searches more difficult. The Excel template uses hyphens as separators and flags spaces or additional hyphens entered inside individual code segments.
Reusing discontinued SKUs
Keep discontinued SKUs associated with their historical products. Reassigning the same code to a new product can mix old and new transaction history.
SKU system checklist
- Each separately managed product or variant has a unique SKU.
- The SKU structure is documented.
- Category, product-type, and variant codes are used consistently.
- Only stable, useful attributes are included in the SKU.
- Price, cost, current stock, and temporary information stay outside the SKU.
- The same SKU is used across operational systems where possible.
- Discontinued SKUs are not reused.
- The master catalog is kept up to date.
- Employees know how to create a new SKU.
- New SKUs are reviewed before they are activated.
Frequently asked questions about SKUs
How long should a SKU be?
There is no universal required length. A SKU should be short enough to use comfortably while containing enough information to distinguish the products and variants your business needs to manage.
Does every color and size need a different SKU?
Usually yes when those variants are purchased, sold, stored, counted, replenished, or analyzed separately. If two variants have independent inventory, giving each one a unique SKU makes that difference visible.
Should a SKU include the supplier?
Usually not. A supplier can change while the product remains the same. Store the Primary Supplier in a separate master-catalog field instead of embedding it in the SKU.
Is a SKU the same as a barcode?
No. A SKU is an internal product identifier created by your business. A barcode is a machine-readable representation of data. A barcode can encode a standardized identifier such as a GTIN, or another identifier depending on the system being used.
Can SKUs contain letters and numbers?
Yes. SKUs are often alphanumeric. Combining short letter codes with a numeric sequence can make a structured SKU both readable and unique.
Can two products have the same SKU?
They should not if they are separate catalog items. A SKU should uniquely identify the product or variant within your internal catalog. Duplicate SKUs can create problems in inventory, sales, imports, and reporting.
Can I change a SKU later?
Some systems allow SKU changes, but frequent changes can make integrations, reports, transaction history, and product reconciliation more difficult. Build a stable structure first and change an existing SKU only when there is a clear operational reason and you understand the effect on connected systems.
Should I reuse a discontinued SKU?
No. Keep the old SKU associated with the discontinued product so historical purchases, sales, returns, and reports continue to refer to the correct item.
Free SKU Generator & Master Catalog Excel Template
Creating SKU numbers is easier when you define the coding structure first and keep every reference in one master catalog.
The free Excel template includes a completed apparel example and lets you create and validate SKUs for up to 300 product records.
The workbook contains three sheets:
- 01_Instructions: workflow, coding rules, validation messages, and limitations.
- 02_Glossary: definitions for SKU, structured SKU, sequence, variants, margins, GTIN, status, and other fields used in the workbook.
- 03_SKU Catalog: SKU generator, validation controls, product information, cost and price fields, supplier, GTIN, notes, and summary indicators.
The generated SKU follows this structure when all segments are used:
Category Code + Product Type Code + Variant 1 Code + Variant 2 Code + Sequence
For example:
APP-TSH-BLK-M-014
The Validation column can display:
| Message | What It Means |
|---|---|
| OK | The required SKU fields and built-in checks passed |
| Complete required fields | One or more required fields are blank |
| Review status | Status is not Active, Draft, or Discontinued |
| Invalid sequence | Sequence is not a whole number from 1 to 999 |
| Review codes | A code segment contains an internal space or hyphen |
| Review variants | A variant name and its code are not completed as a pair |
| Review cost/price | Optional cost or selling-price data are invalid for margin calculation |
| Duplicate SKU | The same generated SKU exists in another catalog row |
The workbook can also calculate Gross Margin $ and Gross Margin % when valid Unit Cost and Selling Price information is provided. These fields are optional and remain separate from the SKU itself.
Important: this workbook creates and checks internal SKUs. It does not create GS1 identifiers, UPCs, EANs, or GTINs, and it does not replace ERP, POS, inventory-management, marketplace, barcode-printing, lot-tracking, or serial-number systems.
The template supports up to two coded variant dimensions per catalog row. If your products require a more complex variant structure, adapt the coding policy to your systems rather than forcing every attribute into the SKU.
Create a SKU system your team can maintain
A useful SKU system is not the one that stores the most information inside the code. It is the one your team can understand, apply consistently, and maintain as the catalog grows.
Start by deciding what needs to be tracked separately. Choose a simple structure, document the approved codes, keep frequently changing information outside the SKU, and maintain one master catalog as the source of reference.
Once the rules are defined, use the free SKU Generator & Master Catalog Excel Template to generate codes, identify duplicate or incomplete records, and keep product information organized in one place.
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