Understanding Bar Codes, ASINs, ISBNs, SKUs, etc.


If you have been selling on eBay or Amazon for a while, you may already know most of this, but I get questions from new sellers often enough that I know there is some confusion out there. So here is an article that explains the basics.

With the millions of products available, how does a seller keep track of the inventory? In the past, businesses hire employees who manually track merchandise causing significant costs in terms of money and time. Good thing, the advent of bar codes had begun.

Bar codes are technically called, Global Trade Item Numbers (GTINs), are unique product identifiers, which make obtaining product information across different databases and platforms easier. It’s a symbol, which, when scanned, will show the unique attribute of a product.

With bar codes, operational efficiency is realized because these entail faster and more accurate recording of information– so time is saved, errors are reduced and all in all, costs are cut. Aside from these, putting barcodes in your products would enable you to meet business regulatory requirements, since agencies and online selling platforms such as Amazon, now require unique identifiers in products.

As a general rule, you need a bar code in order to sell a product in Amazon. Amazon requires this in order to reduce, or even eliminate duplicate product listings and incorrect search matches, and because items with barcodes are more efficient to receive and ship to customers.

So far, there are five main types of barcodes used in Amazon:

· International Standard Book Number (ISBN)– This is found in books, CDs and DVDs and can come in both 13 and 10-digit numbers.

· Universal Product Codes (UPCs)—This code system was developed in the United States and has been widely used in North America, UK, Australia and New Zealand

· European Article Number (EAN)—Invented by the French, this is a superset of the UPC system, and is used worldwide for products that are sold at retail point of sale.

· Japanese Article Number (JAN)—This is what product identification numbers in Japan are called.

· Amazon Standard Identification Number (ASIN)—Amazon assigns its own version of barcodes to items that are uploaded into their inventory. This is a code system that is unique to the Amazon marketplace. If you know the ASIN of an item, you can type it into the Amazon search box and it will come up.

Amazon requires a UPC (or EAN) number for almost any product you list on Amazon. If you want to sell an item that does not have a UPC number, or if you are creating a unique item such as a bundle of products, then you will need to purchase a UPC number. Note – If you are creating an item on Amazon that requires you to purchase a UPC number, you only need the number – not the actual bar code artwork/graphic. This is because you generate your own bar code label when you create a shipment to Amazon. That label identifies both the product and who it belongs to so Amazon knows who to pay when the item sells.

How to Obtain Bar Codes

There are companies nowadays who sell/ lease bar codes.  One service I use is Bar Codes Talk, They have sold over 4 million barcodes (and counting) and have satisfied a lot of clients. But there are plenty of websites that sell bar codes. Another good supplier is Nationwide Barcodes.  Their site also includes a lot of good information.  Bar Codes Talk is very popular with eBay and Amazon sellers.

Ideally, barcodes are integrated into the design of your item, so if what you will be selling is not yet manufactured, then you may want to coordinate with your barcode vendor so that the product identifier will be incorporated with the design. But if your product is already manufactured, then you can still easily obtain bar code labels.

Bar codes help you achieve operational efficiency, plus, it allows you to sell in one of the world’s busiest online selling platforms.

Seller SKUs

SKU stands for Stock Keeping Unit and it’s a number that you generate to help you keep track of your inventory. There are several systems to create and track SKUs. Here is one way I do mine:

The first letter stands for the category of product – J for Jewelry, B for Books, K for Knives and so on.

The next letter is the month I bought the item and listed it on eBay or Amazon, so a SKU that started with B3 would be a book I sent into Amazon in March.

Next, I put the cost of the item. I use the simple “paintbrush” code. Paintbrush is a ten-letter word with no letters that repeat, so each letter stands for a number. A SKU that started out B3PNH would be a book, I sent in March that cost me $1.40. Then I usually come up with some type of abbreviation to identify the product. So if the book was Tom Clancy’s Hunt for Red October the code might be B3PHH-RO. The RO would stand for Red October. (Some other ten-letter words with no repeating letters include: Cumberland, springvale, pathfinder, monkeyspit, motherland, crazywomen and falconview).

If you tend to sell a lot of items from one supplier, another way to go is to use the initials of the supplier and the part number of the item. So for my Novobead jewelry, I might use NB4105. The advantage of this is that I can search the term Novobeads in my Amazon inventory and the SKUs will come up in order. So if I sort by quantity, I can see which beads I am out of, or low on stock and I have a nice list with the part numbers to place on my order sheet. See image below:

The column after the price is quantity inbound.  The next column is the quantity on hand in FBA. (This is the column I sort to see what I am low on).  So if I want to place an order with my supplier, I just use the SKU number without the letters NB as that is the manufacturer’s part number.  The next column is any unfulfillable quantity and the last column shows if any are reserved.

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