Complete Guide to Inventory/Supply Chain Labels

Andrew Musholt
4 min readJun 14, 2022


Whether it’s retail, manufacturing, wholesaling, or any supply-chain organization that ships/receives product, labels are a huge part of how things get done.

When I first started in manufacturing, I was a little overwhelmed by the number of different labels, barcodes, numbers, etc. This is basically the guide I wish I had.

UPC — Universal Product Code

UPC’s are primarily used in retail environments (grocery stores, department stores, etc.)

They are 12-digits long in the United States, and are usually printed directly on the product itself. (If you live in Europe, it’s 13 digits…and they call it an EAN). These 12 digits are strictly numeric.

As the name suggests, these numbers are UNIVERSAL. When you buy a 16 oz block of Velveeta, it doesn’t matter if you buy it at Walmart or Costco — it will have the same UPC.

UPC’s are purchased through and managed by the GS1 (formerly the Uniform Product Code Council).

SKU — Stock-Keeping Unit

A common question people ask: “Are UPC’s the same thing as SKU’s?” and the answer is no.

Unlike UPC’s, SKU’s are INTERNAL tracking numbers…and vary from company to company. If you think of a grocery store, UPC’s are being scanned up front at the checkout. In the warehouse, products are inventoried by their SKU.

Because they are not universal, you may find SKU’s using wildly different schemas from company to company. One company may use strictly numbers, similar to a UPC. Another company might use a combination of letters and numbers. Finally, some companies will embed product characteristics into the SKU…such as the color or model number.

Image by Sabrina Jiang © Investopedia 2020

In the Amazon world, they call their SKU’s “ASIN’s” (Amazon Standard Identification Number)

It is unwise to use another company’s SKU’s for your own (such as your supplier) because your supplier has no obligation to notify you if they change their SKU schema.

MPN — Manufacturer Product Number

Also known as “model numbers”, “item numbers”, or just “part numbers”.

An MPN looks like a SKU, but acts like a UPC. In other words…the MPN number can be a combination of letters, numbers, and special characters (like a SKU) but is used by customers, not for inventory (like a UPC).

An MPN might look something like this: CRT43–HD–91.

It is generally pretty common for various part attributes to be “embedded” in the number (for example, “CRT” above may be short for “cathode ray tube, 43-inches long, high-definition, year 1991”).

Embedding information like this is called “intelligent” numbering. When it comes to intelligent vs non-intelligent (random) numbering, there are pro’s and con’s to each. This article discusses this in depth:

MPN’s are useful for customers because they will often be looking these up on your website for various reasons: installation/setup instructions, repair parts, replacement parts, etc.

Serial Number

UPC’s, SKU’s, and MPN’s are for identifying different types of products. Serial numbers are for identifying specific instances of a product. You use a serial number to track EXACTLY x1 product….usually a high-value/dollar product.

If my manufacturing company produces 16 compressors in a given day, all 16 of those compressors will be stored by the same SKU and sold by the same MPN. But no two compressors will have the same serial number….no matter how many compressors we ever make.

Like SKU’s and MPN’s, serial numbers may (or may not) embed product attributes into the number….such as the year it was produced or the plant it was produced in. Very commonly, they will begin or end with an integer that increments by 1 for each product produced. Example:

1st compressor’s serial number: CMP1990–00001

2nd compressor’s serial number: CMP1990–00002


While customers can look up their product by MPN for basic information, the serial number can be uniquely tied to THEM. This can be very useful for warranty/damage, product recalls, deterring theft, etc.

Lot Number

Also known as a “batch number”

While SKU’s and MPN’s are useful for “types” of products, and serial numbers are good for “1 specific instance of a product”….lot numbers sort of fall in-between.

Lot numbers are a way to track any “batch” or “run” of a product, typically all the same type of product.

They are often tied to a specific supplier/shipment and a specific date, which can be useful for tracking “defective batches” and managing product recalls.

In the food industry, lot numbers can help you manage the rotation of perishables on your shelves.

LPN — License Plate Number

LPN’s are used for tracking a specific pallet/container of product….almost exclusively for inventory.

LPN’s are NOT lot numbers. They are typically much smaller, and more diverse in products.

Lot numbers are generally only 1 type of product or 1 “run”. LPN’s can contain multiple product types and quantities.

Lot numbers are mostly for tracking AFTER being shipped to the customer. LPN’s are for tracking BEFORE being shipped — a customer will likely never see your LPN.

LPN’s overall are meant to be very, very “general purpose” for tracking inventory….they are not limited to a time, product type, etc.

I hope you found this useful! Please feel free to let me know if you have questions, corrections, or anything else.



Andrew Musholt

Full-time web developer, part-time business owner.