Stock Keeping Unit (SKU): What Is It & How Are SKUs Used in Retail

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The world of order fulfilment can seem full of confusing jargon, especially if you’re just starting your ecommerce business. Part of creating an ecommerce order fulfilment strategy involves understanding all of the different parts of successful fulfilment and inventory management.

One important element to get familiar with is the SKU, or Stock Keeping Unit.

In this article, you will learn what a SKU is, how SKUs are used, and how to calculate the number of SKUs in your inventory.

What is a Stock Keeping Unit (SKU)?

A stock-keeping unit (SKU) is a scannable alphanumeric code used to identify a specific product as an inventory control measurement. SKU codes are usually printed on product labels and represent different product characteristics such as colour, size, brand, and are used by traditional retail stores, product fulfilment centres, warehouses, online retailers, and in catalogueueues to track inventory and improve their overall inventory management

Using a SKU and barcodes

A SKU can be any series of numbers that you choose. Unlike aUniversal Product Code (UPC),SKUs are actually unique codes; instead, each retailer has its own variant of SKUs.

There is no rule about creating SKUs, but make sure that everyone at your company understands your SKU system; SKUs are unique identifiers that can easily be, as opposed tobarcodesor UPC codes that often need equipment or software to break down.

Shopifygives the following example for a SKU number:

A SKU for a pair of purple Ugg boots in the Bailey Bow style, size 7 might look something like this: UGG-BB-PUR-07.

The above example is easy to read, shares important information about the product, and follows a clear naming convention.

How SKUs are used in ecommerce

SKUs help you keep track of your inventory with regard to both inbound and outbound logistics, and are especially helpful when working with a third-party fulfilment provider.

When working with a new third-party logistics (3PL) provider, you will likely be asked how many different SKUs you have in your inventory. This helps the 3PL know how much warehousing and storage space you will need in their fulfilment centre, as well as how complex your orders may be.

Many 3PLs store each unique SKU in its own bin or shelf space to optimise picking lists to make the picking and packing process as accurate and efficient as possible.

A 3PL that offers a comprehensive inventory management solution may offer the following services, all of which are based on SKUs:

Overall, 3PLs use SKUs to not only keep track of your inventory, but also to offer customised and in-depth analytics and services for your ecommerce business.

How to calculate the number of SKUs in your inventory

To calculate the number of SKUs in your inventory, you will need to consider all of the different product variations you offer. This includes variations in colour, size, price, and more. The number of SKUs in your online store will be equal to the number of product variations.

If you are a small clothing retailer, your SKU calculations might look like this:

You have a t-shirt that comes in 2 styles, 2 colours, and 3 sizes. Red or blue; v-neck or crewneck; and small, medium, or large. Here are all of the possible product variations:

  1. Red, V-neck, Small
  2. Red, V-neck, Medium
  3. Red, V-neck, Large
  4. Red, Crewneck, Small
  5. Red, Crewneck, Medium
  6. Red, Crewneck, Large
  7. Blue, V-neck, Small
  8. Blue, V-neck, Medium
  9. Blue, V-neck, Large
  10. Blue, Crewneck, Small
  11. Blue, Crewneck, Medium,
  12. Blue, Crewneck, Large

2 colours x 2 styles x 3 colours = 12 variations; you will have 12 SKUs.


SKUs may seem confusing, but they don’t have to be! They are an integral part of inventory management, and successful inventory management is key to ecommerce fulfilment success.

If you are looking for an end-to-end fulfilment solution that includes inventory management, check out ShipBob. See which of your SKUs are selling best, receive automatic reorder notifications based on inventory for each SKU, and access additional advanced reporting about your inventory. Request a pricing quote below to speak with a fulfilment expert. 


Learn more

Learn more about how partnering with a modern fulfilment company can help you manage your SKUs, and get tips for choosing a fulfilment partner. Download “How to Choose a 3PL for Your Ecommerce Business.”  

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Written By:

Rachel was a Content Marketing Specialist at ShipBob, where she created content that helps ecommerce merchants build and grow their businesses.

Read all posts written by Rachel Burns