Did you know that UPC, SKU, and Serial Number are three different unique identifier code? In case you haven’t realised by now, than let’s make it clear from the start, they are fundamentally different codes/number, but has many overlapping features.

With that, what’s the purpose of each code then? Let’s dive into each of them a little more.

Universal Product Code (UPC)

Typically, a Universal Product Code (UPC) is the number (or code) that is unique to a product and it is universal to it. That means the exact same number is used no matter where the product is being sold, you could take a product you buy from one store and it would still be valid in another store.

This is also usually the number with the bar code that is printed on the packaging or cover of the item. Examples include the number printed on the can of a coca-cola bottle or on the wrapping of a cereal bar.

If you are a manufacturer, you might also want to obtain a UPC number from the local authorities or manufacturer’s association so that your products are registered with them.


A Stock Keeping Unit (SKU) is a store specific number and would only be valid at the store where it is being sold it would not be universal. This is usually predetermined by the owner of the store and is it a unique product code used by his/her business.

However, for many small business/store owners, they usually end up using the UPC as the SKU number as there is no reason for creating a new SKU. In fact, they can already track the quantity of the goods just by using the existing UPC.

Serial Number

A Serial Number is a sequential number that is assigned to a single item of a product. The serial number will only be for that one single item. It is there so you can track ownership and warranty information of that item. Serial numbers are common with electronic products.

In a modern WMS software (like the one offered by SmartB), it is easy to create a serial number for each product and this can be printed internally.

Bar Codes, Sizes and Formats

Each of the above UPC, SKU and Serial Number can be read or printed on a bar code. Once a bar code is printed, it makes tracking and recording much easier.

SKU is usually an 8 digit number that you can use to cross reference a product especially when you don’t have the 12 digit UPC.

If you were talking about garments, all red size eight blouses would have the exact same SKU and UPS from the maker for a particular style. Cars and appliances such as TVs and refrigerators would also share skus and upcs, but each would have a unique serial number that is used when requesting repair or other related services.


Learn more about warehouse and supply chain here.