Helping You with Your Amazon FBA Business

Save Time by Creating Custom Merchant SKUs

Hello and hope you are doing well!  In today’s post, I’ll cover why customizing your Seller SKUs will give you quick at-a-glance information that will save you time with various Amazon FBA tasks such as bookkeeping, repricing and overall analyzing.

What is a Seller SKU?

This is Amazon’s definition:

A SKU (stock keeping unit) is a specific merchant’s product identifier. The SKU is a critical piece of data in every inventory file that you submit to us. Amazon uses the SKUs in your inventory file to associate your products with the appropriate product detail page in our catalog (if one already exists). 

I don’t claim to understand all of Amazon’s definitions, but I do know that our products need a unique Seller SKU.  Seller SKUs are created when you list your inventory items.

Seller Central’s Inventory->Add a Product->Offer Info Page

In my first 14-15 months as an Amazon Seller, I left the Seller SKU field blank and let Amazon generate them for me.  Once I started creating my own Seller SKUs, the time that I spent inputting my buy costs into my repricer decreased dramatically.

Other Names for Seller SKU

Seller SKU is also referred to as SKU, Merchant SKU or MSKU.  For the remainder of this post, I’ll use the MSKU abbreviation.

Auto-Generated vs. Custom MSKUs

Below are two example MSKUs.  One is generated by Amazon and the other is customized:

  • BU-SLX3-CCX8
  • SH-060117-FF-1799

The 2nd one is the way that I currently customize my MSKUs.  By just taking a quick glance, I know that:

  • It’s a shoe (SH)
  • The list date is 06/01/17 (060117)   **I use list dates instead of purchase dates.
  • It was purchased from Famous Footwear (FF)
  • The buy cost is $17.99 (1799)

How Custom MSKUs will Save You Time

Repricing:  When you reprice your products, you need to know your buy cost so that you can set your selling price.  Without knowing it, you can price it too low so that you lose money.

The above image is from my BQool Repricer dashboard.  Going through each of my products to enter the buy cost is faster now that I have the buy cost coded into the MSKU.


One way to calculate your monthly cost of good sold (COGS) is to use the Custom Transaction Report from Seller Central.  Once you download it and format it so it’s easy to read, you can go through and enter your buy costs for each sold item.  Having the buy cost coded into the MSKU eliminates the need to go back and search for your buy costs from receipts or other spreadsheets.

In the above image, I paid $19.99 for the first item and $24.00 for the second item.

Business Analyzing 

Many times you’ll have your data in a grid or spreadsheet that you can sort.  Then if you sort by MSKU, you can get helpful information.  For example:

The above image is from my May Custom Transaction Report sorted by MSKU.  These rows tell me that I sold 11 wholesale products (WS) from the company coded as EL.  The product coded with the “5” at the end is the best seller in May.

There’s really no limit on how you can code your MSKUs and how you can sort them to produce reports that will help you grow your business.

Spreadsheet Users: Save more time with Caleb Roth’s Tracking Spreadsheet because it will calculate the COGS and create reports for you.

Create Your own Custom MSKUs

You have 1 to 40 characters to use for your Merchant SKU.

How you format it is up to you and it should contain information that will give you the “at-a-glance” information that you need.  A few ideas are:

  • Purchase or List Date
  • Store Name
  • Buy Cost
  • Minimum and/or Maximum Selling Prices
  • Product Category
  • Ranking on the date that you’re listing it
  • Source – who found the product or how you found the product
  • Condition (if you’re selling books)
  • Brand, Size, Gender, Color
  • FBA or Merchant-Fulfilled Item

As you start customizing your own MSKUs, you’ll probably change the format a few times.

Custom MSKU Examples

These examples are taken from my actual inventory.  You’ll notice that the MSKUs evolved over time.

  • LR-POYN-BC52 – Amazon generated this one.
  • FBA 072715 03 – Added in “FBA,” the buy date and a number on the end to keep the MSKU unique.
  • Shoes-05/19/16-000002 – Added the category (Shoes).
  • GM-07-13-16-_4-1.25 – GM stands for General Merchandise and added the buy cost.
  • Book-Amazon-072216-5-10.41G – Added the supplier (Amazon) and the book condition.  The letter “G” means that the book is listed as Good.
  • TOY-120416-_1-FM-4.24 – Can you guess what this means?
  • SH-031017_1-W9DSW1297 – At one time I included the shoe size.  In this example, it’s a Women’s Size 9.
  • SH-051917_7ZU2264Q – The Q at the end means that this was a lead from Quincy Lin’s shoe list.

Don’t worry about buyers seeing how much you paid for an item.  Amazon doesn’t include the MSKUs with the products that they ship out.


Q: Will 3rd-Party Listing Services such as InventoryLab let you create Custom MSKUs?


A: Yes and listing products is faster than it is in Seller Central because then you can enter a MSKU prefix.  This saves you time because you don’t need to enter the same “common” info over and over again.

Q: If I buy the same product again at a different price, do I need to create a new MSKU?
A: I always use the original MSKU because Amazon doesn’t want us to create multiple MSKUs for the same product.  This means that there will be products where the MSKU price is wrong.  Typically I know in my head which products these are and know how to find the correct price if needed.

Q. What if I purchased the same toy from Walmart and Target?
A.  This happens to me a lot in the 4th Quarter.  I just code the MSKU with the store name that I purchased the most units from.

InventoryLab pulls some of their report data from these fields and not from the MSKUs.

Even if your MSKU info isn’t 100% correct on all of your products, your reports from InventoryLab, Caleb’s Tracking Spreadsheet and other 3rd-party services will be.  This is because they don’t pull the data from your MKSUs.

Share Your MSKUs!

Do you already create your own Custom SKUs?  If so, please share the format in the comments below!


{ 5 comments… add one }
  • Ree Klein June 16, 2017, 1:24 pm

    Hi Diana,

    This is a great post. The SKU is really important to customize for private labelers, too. I wish I had figured that out long ago. It is helpful in so many ways but here’s one more….

    When you print your shipping labels for your FBA shipments, the SKU is printed on the shipping label. When it’s just some random number assigned by Amazon’s system, things can get confusing when preparing shipments. When you use a customized SKU, it’s much easier to ensure the right label gets on the right box!

    Caveat — I tend to ship one SKU per carton so I’m not sure how the shipping labels will print if there are multiple SKUs per carton. If anyone knows, please enlighten us all!


    • Diana June 18, 2017, 3:08 am

      Hey Ree,

      I can see where having your own customized SKU makes it much easier when shipping.

      To be honest, I never noticed the MSKUs on the shipping labels. But it could be because I’m sending in multiple SKUs in the same box and am not sending in PL products. But now you have me curious and in a few weeks when I send my bundles in, I’m going to send multiples of just one SKU/Bundle in the same box and check the shipping label!

      As always, thanks for reading my posts and commenting!


  • Bob Dykes June 16, 2017, 2:51 pm

    Hey Diana,

    You’ve heard the expression that “Great minds think alike” Well, my MSKU’s happen to be almost identical to yours Diana with the exception of adding a little more info. I like to know the quantity and condition of my order as well as the number of items I purchased in that particular order.

    I add the condition. If “new” I use “n” and if used I skip using the “u” for used and just use “Ln” for Like New, “vg” for Very Good, “g” for Good” and “a” for Acceptable.

    Next, I add the the position in the purchase the item is in. If it’s the first item in the order it’s a “1” and if it’s the third item then it’s “3”.

    Then, I add the amount I’ve purchased whether it’s 1, 5, 10 or however many of the item I’ve bought.

    So, my MSKU’s end up very similar to yours and looking like this “032817-trus-n-1-2-2999” which translates to Purchased on March (03) the 28th (28), from Toys R Us (trus), in New (n) condition, this is the first (1) item in this order, there are two (2) of them and I paid $29.99 (2999) each.

    I’m always in favor of simplifying or speeding things up so I will have to give your tip on determining COGS a try. I either didn’t know or didn’t think about using my MSKU with the Custom Transaction Report so thanks for letting us know about it.


    • Diana June 18, 2017, 2:36 am

      Hi Bob,
      I’m learning from your “Great Mind” because I never thought about putting the quantity in the MSKU!

      I do use Caleb’s spreadsheet for my monthly COGS number. But if I didn’t have any automated COGS tracking software, I would use the Custom Transaction Report as I mentioned. In the old days, I would go back and search for every Buy Cost and that does take time especially when your volume increases. Having the Buy Cost in the MSKU does speed things up.

      Thanks for sharing your MSKU method!



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About Diana

I am working towards creating a full-time income by selling on Amazon. It's a lot of work but very fun! If you're interested in selling on Amazon, be sure to follow my blog as I'll be providing you with lots of tips!

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