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When you first become an Amazon seller, it can be quite overwhelming to understand all the moving parts and new terms you have to use.
You need to know what things like MSKU, ASIN, UPC codes, and seller performance metrics mean for your business in order to run it successfully.
Quick Summary of This Guide
In this post, we will expand upon what seller SKU is and what it means for your business as an Amazon seller.
We will also go over the differences between seller SKU and FNSKU, and also go over some SKU examples.
So, without further ado, let’s get into it.
What is Seller SKU on Amazon?
SKU stands for Stock Keeping Unit and it is a unique alpha-numeric string that is assigned to uniquely identify the products you sell on Amazon.
You can choose to assign SKUs yourself or you can choose to generate them via Amazon.
If you assign SKUs yourself, it’s important that you follow some sort of system in order to identify the types of products you’re selling. We will elaborate on this in our SKU examples.
SKUs are not a new concept. In fact, they are used in traditional retail as bar codes as well as e-commerce and online retail where they are assigned to all products within the system.
Please note that SKUs are different from UPC codes. SKUs are required for internal management purposes whereas UPC codes are used for external item identification purposes.
SKUs on Amazon is limited to under 40 characters. They are used to help Amazon sellers keep track of their inventory and goods.
The Seller SKU (also known as the MSKU) is one of the final strings that are assigned to a product.
When a product is first added onto the Amazon platform, it starts out with its UPC code. After that, it’s assigned an ASIN (Amazon Standard Identification Number), then it gets the seller SKU and finally, the FNSKU.
What’s a UPC Code?
UPC stands for Universal Product Code and it is the system that is used globally to identify products by manufacturers.
Basically, you can think of UPC as the system that is used globally outside of the Amazon platform.
It’s a barcode symbol that encodes a 12-digit number used to identify the product.
What is ASIN?
ASIN stands for Amazon Standard Identification Number (formerly, it was Amazon Stock Identifier Number).
It is an alpha-numeric string assigned by Amazon to all the physical products within its catalog in order to identify them.
Please note that the ASIN and the seller SKU are two different strings used for different purposes.
The ASIN is always assigned to products by Amazon whereas the seller SKU is something that you define on your own for your products (though, you have the option of making the SKUs yourself or having Amazon generate them for you).
You can find the ASIN for all products sold on Amazon in the Product Information section of the product listing as shown:
What’s the Difference Between Amazon Seller SKU and FNSKU?
We’ve established that the Amazon seller SKU is something you can assign yourself to your products in order to uniquely identify them within your catalog.
On the other hand, the FNSKU, which stands for Fulfillment Network Stock Keeping Unit, is an alpha-numeric string assigned by Amazon to Amazon FBA products.
Hence, an FNSKU is only assigned to products that are Fulfilled by Amazon (also known as Amazon FBA), i.e., products that will be shipped to Amazon fulfillment centers.
The purpose of the FNSKU is to ensure that the sale of your products is correctly attributed to your business.
Since Amazon manages millions of products, this is essential so that you receive the income you deserve from the sale of your products.
If you’re an Amazon FBA seller, then an FNSKU will be assigned to the product(s) you’re selling.
When you ship your product(s) out to an Amazon fulfillment center, you will need to ensure that the FNSKU is added to the shipping label so the product can be attributed to your business.
What Needs to be Included in an Amazon Seller’s SKU?
There’s no real rule as to what you need to include within a seller SKU.
However, as a rule of thumb, it’s a good idea to have some identifiers within the SKU that can help you quickly identify what the product is as well as what variant it is.
Essentially, you should assign SKUs so that you are able to:
- Uniquely identify and categorize items by size, color, or type
- Quickly pack and ship products from the warehouse
- Easily manage your inventory that is being shipped using different channels on Amazon
In order to include as much information about the product within the seller SKU, you can look towards identifiers such as:
- Product type
And other attributes that may apply to the product.
Of course, depending on the product, these identifiers can vary. It’s important to use your own judgment to identify which attributes are the most significant and need to be included within the seller SKU.
Seller SKU Examples
Let’s assume that you’re selling t-shirts on Amazon of different designs, sizes, and colors.
The following are some examples you could use to identify the different t-shirts you’re selling:
- Design 1, small, blue shirt = D1-S-B
- Design 1, medium, blue shirt = D1-M-B
- Design 1, large, blue shirt = D1-LB
- Design 1, small, redshirt = D1-SR
- Design 1, medium, redshirt = D1-M-R
- Design 1, large, redshirt = D1-L-R
- Design 2, small, green shirt = D2-SG
- Design 2, medium, green shirt = D2-M-G
- Design 2, large, green shirt = D2-L-G
After looking at these examples, we’re sure that the usefulness of seller SKUs will have become very apparent to you.
When you add more designs to your catalog, make sure that you follow the same format. So, for example, if you add a third design, then the SKU would start with “D3”.
It’s important that once you define a format that you stick to it. Changing stuff mid-way will only cause confusion.
So, Should I Always Create My Own Seller SKUs or Should I Let Amazon Do it?
In general, most sellers on Amazon recommend that you spend some time developing a system to create your own SKUs.
It’s a good idea to decide a format and then assign your own seller SKU to every different type of product you have.
There are a few reasons why people discourage new sellers from letting Amazon generate SKUs for them.
Some of these reasons are:
- If you happen to be selling the same products on different stores on Amazon, then Amazon will define different seller SKUs for those products. So, as an example, if you’re selling a shirt in two different stores, it will have an SKU of ST-35-TRP-7 on one store and an SKU of 58-YYG-89. As you can imagine, keeping track of these numbers will be extremely difficult.
- The generated SKUs that Amazon assigns to your products will be meaningless to you and your team (if you have one). One of the main advantages of SKUs is to quickly identify the products in your inventory. Amazon-generated SKUs do not fulfill this purpose at all. In fact, they hinder it.
As opposed to letting Amazon create your SKUs, developing your own system and assigning SKUs yourself has a ton of advantages.
Some of these advantages are:
- It’s easy to group the same items of the same type together as well as items that are selling well/are popular.
- It allows you to create an extensive product identification system that will come in very handy once you start to scale up your business and increase the number of products you sell.
- It helps out a ton when you’re trying to create sales reports by different metrics such as season, channel, or product type.
While creating your own SKUs may seem like a tedious task when you’re just starting out as an Amazon seller, we implore you to take some time out to do so.
We promise that your future self will thank you.
Some More Identifier Ideas for SKUs
We gave some examples above in the post about how you can create SKUs based on size, color, and type.
While this is a fairly rudimentary approach, it can still be very useful for new sellers.
However, as you start to scale up your business, you’ll need to have other identifiers to help you out too.
Some examples of such identifiers are:
Say that you’re getting the same product to sell from two different distributors: one distributor is in China while the other one is in France.
You can identify products coming in from China by having the identifier “CN” within your SKU whereas you can have the identifier “FR” for the products that are coming in from France.
But how does knowing the distributor for the product help you?
Well, depending on the distributor, the quality of your product can vary and as a result, this can affect sales.
After a few months of selling the product, you may notice that a much higher number of products with the CN identifier have been sold whereas products with the FR identifier are still lying in your warehouse.
Thus, you can make the decision of severing ties with your French distributor and only working with the Chinese distributor to increase sales.
This can be a powerful identifier when used correctly.
Usually, it is used within the SKU format to identify certain trends of when certain types of products will be more popular among consumers.
For example, let’s assume that you bought winter clothes at a cheap price in April in order to sell them in the winter season.
You can have an identifier within your SKU format that tells you when the clothes were bought. Let’s say, you have “APR” somewhere in SKU to identify that the clothes were bought in April.
Then, once winter rolls around, you can quickly identify the winter clothes you bought in April because they’ll have the “APR” identifier within their SKU.
This one is fairly common and it’s definitely something you should consider using if you’re selling a mix of both new and used products.
Simply having an identifier which states whether the product is in new condition or if it’s used can help out a lot when managing inventory and sending products to Amazon fulfillment centers.
Wrapping Things Up…
That’s pretty much it.
We hope you have a better understanding of SKUs, FNSKUs, UPC codes, and ASINs now. It’s highly important that you know what all of these numbers are before you start selling on Amazon.
Do you have some neat tricks regarding identifiers to use in SKUs? Let us know in the comments below.