Understanding your Amazon seller SKU, how to customize it, what information to include, and why any of this matters.
Video: Why (& how) to add data to your seller SKU
The power of customizing your inventory SKUs
I’m about to break down how to add custom data to your Amazon seller SKU, and exactly how this will streamline your repricing, accounting, and more.
First, an intro-guide to your Amazon seller SKU: What it is, and more…
What is your Amazon seller SKU?
For every item in your Amazon inventory, you have a SKU (also known as Merchant SKU or MSKU). This is basically a unique identifier for everything you have for sale on Amazon, and is specific to you and your account (which makes it different than an ASIN).
You can see it in your Amazon inventory here:
Normally, you would never have any reason to think about your SKU. You can sell a billion items for a thousand years on Amazon and never have to think about – or look at – your seller SKU.
But its possible to customize your SKUs, and embed certain information (up to 40 characters). And that’s when things get interesting (more on that in a second)…
How are SKUs normally generated?
When you list an item for sale on Amazon, you’re given the option of creating your own SKU, or letting Amazon generate one for you. Most people opt for letting Amazon handle this. Amazon will just create a random blog of letters and numbers that have no meaning whatsoever.
Or, At this step of listing inventory, you can also opt to add your own SKU manually.
As a third option, your listing software can generate a SKU for you (if you’re using listing software). This gives even more flexibility .Most (or all that I’ve seen) listing software lets you auto-insert certain text strings to your SKU, and customize it more easily.


What is the difference between a SKU, MSKU, FSKU and ASIN?
It may seem complicated keeping track of all these, but its really not. Here’s the simple version:
- SKU and MSKU are the same thing.
- FSKU is for FBA sellers only, and is the number/letter combo on the FBA label you print for each item. There’s no reason you need to know this ever, for any reason.
- ASIN identifies a product in Amazon’s catalog. It is specific to each item and item variation. (For most books, the ASIN is the same as the 10-digit ISBN).
A closer look at the difference between SKU and ASIN
The ASIN is the unique identifier Amazon assigns to every item on Amazon. This is publicly visible. One way to look at the ASIN is that it’s item specific, not seller specific. A product’s ASIN is the same for every seller, and can’t be customized or changed.
The SKU is both item specific and seller specific (although its possible to have multiple SKUs for the same product in your account, if you create a different listing for each). The SKU only exists inside your Amazon seller account, and is for your reference only.
Make sense?
What reasons are there to customize your SKU?
Ok, so if we’re here to talk about customizing your SKUs, why would you want to?
The general idea is that by adding certain data to your SKU, you can know a lot about your product at a quick glance. From average sales rank to item cost to listing date to more – you can pack a lot of info into the SKU that you would otherwise have to click around to multiple places for (or wouldn’t be able to access at all).
More specifically, there’s four main reasons you’d want to edit your SKUs (and this list probably doesn’t cover them all):
Manual repricing: Having access to key data that affects how you reprice an item is huge. If you’re repricing your inventory manually, having granular, item-level data allows for more precise repricing.
Repricing software: Some Amazon repricing software tools let you to set repricing rules based on SKU. This allows you reprice items according to specific formulas, even within product categories and sales rank ranges.
Accounting: Get more specific accounting info for your item, such as the ROI for specific sources or products.
General inventory management: This is a catch-all for every other reason various item attributes can help your business. From tracking sales trends to tracking specific sources to finding where an item is located (if you’re selling Merchant Fulfilled) and a lot more.
How do I do it?
Personally, the only reason I customize my SKUs is for repricing. It’s extremely powerful to have certain data available in your SKU at a glance to inform my repricing decisions for each item.
The 9 types of data you can add to your Amazon seller SKU
This is where the rubber meets the road: Here is the most important info you can “code” into your SKUs, and why each one is important:
1. Type of product
What this is: Adding the product category to your SKU. For example, Book, Video Game, etc.
Why this is useful: Being able to see what type of product the item is. This wont’ be terribly useful if you aren’t using any 3rd party software tools, since the product category is visible on your Inventory or Manage Pricing pages.
SKU example: BOOK-340908
2. Subcategory of product
What this is: Adding a subcategory to your SKU. For example, denoting an item as a textbook or an audiobook.
Why this is useful: Has wide relevance for a variety of inventory management, accounting, and repricing applications. Personally, this is most valuable in my business because I reprice different subcategories different ways. I have one very liberal repricing formula for textbooks, and another more conservative repricing formula for audiobooks, among other subcategories.
SKU example: BOOK-TEXT-340908
3. Inventory source
What this is: Adding a code for where this item was purchased.
Why this is useful: Among others, seeing at a glance where you’re sourcing high-selling or slow-selling inventory.
SKU example: BOOK-TEXT-ALTHRIFT-340908
4. Average sales rank
What this is: Adding the average sales rank to a SKU.
Why this is useful: Average rank is the best measure of an item’s demand (not just better than its current “best seller rank”/BSR, but better than eScore as well). This is particularly useful when repricing, since you should always factor Amazon sales rank into any repricing decision. And current sales rank can be very deceiving.
SKU example: BOOK-TEXT-ALTHRIFT-349k-340908
5. Purchase price
What this is: Adding the price you paid for an item in the SKU.
Why this is useful: Useful for accounting and repricing. For example, knowing what you paid for something can resolve any repricing dilemmas you encounter about whether to drop the price of an item, or hold your ground and wait for it to sell. If you can see what you paid, you might choose to not settle for a sales price that will yield you less than that amount.
SKU example: BOOK-TEXT-ALTHRIFT-349k-3-340908
6. Breakeven sales price
What this is: Adding the sales price at which you would break even on this item.
Why this is useful: For the exact same reasons covered above. The breakeven price is just a more specific and probably useful data point for the same purpose.
SKU example: BOOK-TEXT-ALTHRIFT-349k-10.4-340908
7. Condition
What this is: Adding the condition of the item in the SKU.
Why this is useful: The most common application for this is for sellers doing the online arbitrage model, where they add the condition of the item as described by the seller they purchased from. This allows them to detect any discrepancies between what they thought they were purchasing, and what they ultimately received and listed.
SKU example: BOOK-TEXT-ALTHRIFT-349k-10.4-VG-340908
8. Date listed
What this is: Adding the date you listed an item for sale in your SKU.
Why this is useful: This is among the least useful attributes, since you should be able to see the date an item was listed on Amazon either inside Seller Central, as well as any 3rd party software you’re using to manage or reprice your inventory. But having all useful info in your SKU allows you to get everything you need in one place.
SKU example: BOOK-TEXT-ALTHRIFT-349k-10.4-VG-4-8-23
9. Location
What this is: Adding the location of an inventory item in your warehouse or storage space (for sellers with Merchant Fulfilled inventory only).
Why this is useful: Again, if you’re selling Merchant Fulfilled, this allows you to know where to find an item at a glance.
SKU example: BOOK-TEXT-ALTHRIFT-349k-10.4-VG-SHELF6-4-8-23
How do you decide what attributes to add to your SKU?
Most sellers will not include even half of these in their SKU. So don’t get overwhelmed thinking you need to start stuffing your SKUs with every data point listed above.
Which ones you use is going to come down to which of the four main custom SKU uses (manual repricing, repricing software, accounting, or inventory management).
For a larger Amazon selling operation, you may want to include most or all of the above data points.
For an average/smaller business, you may opt for the basics. I would consider the top 3 most fundamental attributes to be:
- Average rank
- Subcategory (if you’re selling books)
- Purchase price
That would be my top three.
Endnote
For beginners, this is not something I would encourage you to master while you’re still figuring out the rest of the business. This is more of “Phase Two” move, once you have traction and revenue coming in.
For those with an established Amazon business, customizing SKUs is a poweful way to both streamline your accounting and inventory management, and extract more profit from your repricing efforts.
-Peter Valley
PS: Did I miss any useful data you can add to your SKUs? Drop a comment below.


Besides textbooks & audio books, what are the other book subcategories you differentiate?
Distant 3rd and 4th place: seasonal demand books (test guides, Christmas etc), books where I’m the only seller.
Even average rank changes regularly. Doesn’t that make your SKU kind of out of date after a little while?
When you’re looking at annual average rank, it really shouldn’t shift dramatically for a year or more. Which is usually enough time for a book to sell.