If you sell online, you have probably seen the field called SKU in your shop system, on eBay, Amazon or in a listing tool. At first, it may look like just another technical field you can skip.
But in practice, SKU is one of those small things that can save you a lot of time later.
SKU stands for Stock Keeping Unit. In simple words, it is your own internal product code. You create it yourself and use it to identify products in your warehouse, shop system, marketplace listings, orders and reports.
It does not have to be complicated. A good SKU should simply tell you which exact product or variant you are looking at.
For example:
TSHIRT-RED-L
This could stand for a red T-shirt in size L. Another variant could be:
TSHIRT-BLUE-M
That is already much clearer than trying to manage everything only by product names.
What does SKU mean?
An SKU is a product code created by the seller. It is not the same as an EAN, GTIN, UPC, ISBN or barcode.
Those codes are usually official product identifiers. They are often assigned by the manufacturer or used globally to identify a product across different systems.
An SKU, on the other hand, is mainly for your own organization.
You decide how it looks, what information it contains, and how detailed it should be. A typical SKU can include product type, color, size, length, model, material, package size or variant.
Examples:
TROUSERS-BLACK-XL
CABLE-USBC-2M
CREAM-DAY-50ML
Each of these codes gives you a quick idea of what the item is without opening the full product description.
Why SKUs are useful in online selling
When you only have a few products, you can probably manage everything by name. You remember the items, you know what is what, and you can find things quickly.
But once you have 100, 500 or 1,000 products, especially with variants, it gets messy fast.
Product names are not always precise. One product can have a long title on eBay, a slightly different title on Amazon, and another name in your shop system. The SKU gives you one fixed internal reference point.
This is especially useful for variants. A black hoodie in size M is not the same stock item as a black hoodie in size L. They may belong to the same product family or marketplace listing, but in your warehouse they are two different items.
The same applies to bundles, multipacks or products sold differently across several marketplaces. The official product code may describe the product itself, but the SKU can describe how you manage and sell it.
How SKUs help with inventory management
An SKU is not the only way to identify a product. In some cases, you can also work with EANs, GTINs or barcodes. The difference is that an SKU is your own internal code, so you can build it around the way your business actually works.
This is useful when the official product code is missing, not detailed enough or does not match your internal stock structure. For example, you may sell the same product as a single item, a bundle or in different marketplace listings. The EAN may still describe the product itself, but the SKU can describe how you manage it in your own system.
That makes daily work easier. Your team can quickly see which exact product, variant, package or warehouse item is meant. It also helps when products have similar names, when titles differ between eBay and Amazon or when you want to connect several listings to one internal stock item.
So the SKU does not replace official product codes. It gives you an additional layer of control that is built for your own processes.
SKU and automation
Many ecommerce systems use SKUs to connect product data, orders, stock levels and shipping processes.
When an order is placed, the system can identify the sold product based on its SKU. Then it can update the stock, prepare the order and help your warehouse team pick the right item.
This is where SKUs become more than just “nice to have”.
They are often the foundation for automation. Clean SKUs make it easier to automate stock updates, order handling, imports, exports and marketplace synchronization.
If your SKUs are missing, duplicated, or random, automation becomes harder. The system may not know whether two listings are the same product, two different products or two different ways of selling the same item.
That is why it is worth setting up a proper SKU structure early, even if it feels like extra work at the beginning.
Why a good SKU system is worth the effort
A good SKU system helps not only in the warehouse. It also helps with sales analysis, purchasing and planning.
When your products are clearly organized, you can see which colors sell best, which sizes move quickly and which variants are slow.
For example, you may notice that black T-shirts in sizes M and L sell much faster than other variants. Or that a specific cable length is much more popular than the others. With clean SKUs, this kind of analysis becomes easier.
Customer service also benefits from SKUs. If a customer asks about an item, your team can find the exact product faster, even if the title is long, translated, or slightly different across marketplaces.
SKU in Eselt
Eselt also works with SKUs to assign products and variants clearly, especially when you manage many items for eBay or Amazon.
If you sell products in different sizes, colors, or versions, each variant should have its own SKU. For example, one hoodie in five sizes and three colors is not really one stock item, but several variants that need to be identified separately.
If your SKU field is empty and you send a product to a marketplace for the first time, Eselt can also fill in the SKU for you. Still, it is usually better to use your own clear SKU structure from the beginning, because it makes products easier to edit, organize and understand later.
Generate Stock Keeping Unit / Variation SKU in Eselt
In Eselt, you can also generate a Stock Keeping Unit, also called a Variation SKU, for product variants.
Screenshot: Generate Stock Keeping Unit (Variation SKU) in Eselt
This can be helpful if your products do not yet have SKUs or if you want to make sure variants are easier to manage inside the system.
Even when a tool can generate SKUs for you, it is still worth thinking about the structure. The best SKU system is one that your team can understand and use in daily work.
How to create a good SKU
A good SKU should be short, clear and logical.
It should contain the most important product information, but not everything. If the SKU is too long, people will not enjoy working with it.
Good examples are:
TROUSERS-BLACK-XL
CABLE-USBC-2M
CREAM-DAY-50ML
The structure depends on what you sell. For clothing, size and color are usually important. For electronics, cable type, length, wattage or model can be useful. For cosmetics, product type, variant and volume may make more sense.
The most important thing is consistency.
If you decide to use this structure:
PRODUCT-COLOR-SIZE
then use it everywhere.
Do not create one SKU as TSHIRT-RED-L, another one as L-BLUE-TSHIRT, and another one as SHIRT_GREEN_SIZE_M. Technically, those codes may work, but in daily business they will create confusion.
What should you avoid when creating SKUs?
Avoid spaces in SKUs.
Instead of:
T Shirt Red L
use:
TSHIRT-RED-L
Spaces can cause problems in imports, exports, spreadsheets or integrations. Hyphens or underscores are usually safer.
You should also avoid special characters such as &, %, $, #, / or similar symbols. They may work in some systems, but they can create problems in others.
Try not to make SKUs too general.
For example:
PRODUCT-12345
This may technically identify a product, but it does not tell your team anything useful.
At the same time, do not make SKUs too long. A good SKU should give useful information, but still be easy to read and use.
Common challenges with SKUs
The biggest problem with SKUs is not creating one code. That is easy.
The real challenge is creating a system that still works when your product range grows.
Many sellers start by creating SKUs randomly. At the beginning, this does not feel like a problem. But after some time, the product list grows, more variants are added, and suddenly nobody knows what the codes mean anymore.
That is why it is better to define a simple structure early.
You do not need a perfect system from day one. But you should have a system that is logical enough to grow with your business.
For larger product ranges, tools like Eselt, shop systems, inventory management software or ERP systems can help keep everything organized. But even the best tool works better when the underlying product data is clean.
Conclusion
An SKU is a simple internal product code, but it can make everyday ecommerce work much easier.
It helps with inventory management, order processing, stocktaking, sales analysis, customer service, and automation. It also makes it easier to manage products across marketplaces like eBay and Amazon.
A good SKU system does not need to be complicated. It should be clear, consistent, and easy to understand.
If you sell online and do not yet use proper SKUs, it is worth starting before your product range becomes too large. Fixing messy product data later is usually much more painful than setting up a clean structure early.
With Eselt, SKUs can help you manage products and variants more clearly for eBay and Amazon. A clean SKU structure is therefore a good foundation for better product organization and smoother marketplace workflows.
