What Is an ASIN Number? Amazon's Product ID Explained

What Is an ASIN Number on Amazon?

An ASIN is a 10-character code — letters and numbers, always starting with a letter for non-book products (for example, B0C7K5N9QW) — that Amazon assigns to every item in its catalog. It is Amazon's own way of saying "this is one specific product." Whether ten sellers or one seller offer that product, they all list against the same ASIN, and that single code ties together the title, images, reviews, ratings, Best Sellers Rank and price history for the item.

If you sell on Amazon, the ASIN is the number you will use more than any other. It is how you look up a competitor, how you track a keyword rank, how you pull a sales estimate, and how Amazon decides which listing your offer attaches to. Understanding what an ASIN is — and what it is not — saves you from duplicate listings, lost reviews and wasted ad spend later on.

What Does ASIN Stand For?

ASIN stands for Amazon Standard Identification Number. Amazon introduced it because it needed one consistent identifier across a catalog of hundreds of millions of products sourced from millions of sellers. Universal barcodes like UPCs work well between retailers, but Amazon wanted an internal reference it fully controlled — one that could also cover products that never had a barcode, such as digital items, bundles and handmade goods.

Is an ASIN the same as an ISBN?

For books, yes. Amazon uses a book's ISBN-10 directly as its ASIN, which is why book ASINs often contain more digits and look different from the B0… codes on physical products. Every other product category gets a freshly generated 10-character ASIN.

Where to Find an ASIN on Any Listing

1. In the product URL

The quickest method. Open any Amazon product page and look at the address bar. The ASIN is the 10-character block right after /dp/ or /gp/product/ — for example, amazon.com/dp/B0C7K5N9QW. Everything after that code is tracking data you can ignore.

2. In the "Product information" section

Scroll down the listing to the Product information or Additional information table. The ASIN is listed there as its own row, alongside details like item weight, dimensions and the date first available.

3. With a lookup tool or extension

If you are checking many products, a dedicated tool is faster than copying codes by hand. Squatio's Amazon ASIN lookup tool takes any ASIN and returns the keywords the listing ranks for, its price and BSR history, and competitor benchmarks in one view. The Squatio browser extension shows the same data as an overlay while you browse Amazon.

ASIN vs UPC vs GTIN vs FNSKU

These four identifiers get mixed up constantly. Here is how they differ.

ASIN — Amazon Standard Identification Number

Internal to Amazon. Identifies a product listing on the Amazon marketplace. Generated by Amazon, not chosen by the seller. One per product.

UPC / EAN — the retail barcode

A global standard owned by GS1, used across every retailer. Twelve digits for a UPC (North America), thirteen for an EAN (Europe). Most sellers buy UPCs from GS1 and supply one when creating a new Amazon listing; Amazon then issues the ASIN.

GTIN — the umbrella term

Global Trade Item Number is the family name that covers UPC, EAN and ISBN. When Amazon asks for a "product ID" during listing creation, it accepts any valid GTIN. Sellers without one can apply for a GTIN exemption.

FNSKU — Fulfillment Network Stock Keeping Unit

Amazon-specific, but different from the ASIN. The FNSKU is the barcode Amazon puts on each physical unit in an FBA warehouse so it knows which seller's inventory it is. Two sellers can share an ASIN but each has their own FNSKU for their stock.

How ASINs Work for Amazon Sellers

One ASIN, many offers

An ASIN is a shared listing. When you sell a product that already exists on Amazon, you add your offer to its ASIN rather than creating a new page. All offers compete for the same Buy Box, and the listing's reviews and ranking history belong to the ASIN, not to any one seller.

Parent and child ASINs

Variations — sizes, colors, packs — are handled with a parent ASIN that is never sold directly and several child ASINs that each represent one buyable variation. Reviews usually roll up to the parent so a new color benefits from the family's existing feedback.

Duplicate ASINs and listing hijacking

Problems start when the same physical product ends up on two ASINs — sales and reviews split, and neither listing ranks as well as one combined page would. Sellers also watch their ASINs for hijackers: unauthorized third parties attaching counterfeit offers to a brand's listing. Monitoring who is on your ASIN is part of routine account health work.

When Amazon creates a new ASIN

Amazon generates a new ASIN when a genuinely new product is listed with a valid identifier. It should not create one for a product that already exists — doing so on purpose to escape bad reviews violates Amazon policy and the duplicate is typically merged back.

How to Look Up Any ASIN

Once you have an ASIN, it becomes the key to almost every piece of research:

Analyze a single listing

Paste the ASIN into the ASIN lookup tool to see its keyword rankings, estimated sales, price and BSR history, and how it stacks up against close competitors — the context a raw code alone can't give you.

Reverse-engineer a competitor's keywords

Feed a competitor's ASIN into the reverse ASIN lookup and you get every search term their listing ranks for — the starting point for your own title, bullets and backend keywords.

Research a whole niche

Collect the ASINs of the top listings in a category and compare them together with product research to judge demand, competition and pricing before you commit inventory.

Frequently Asked Questions

What is an ASIN number?

An ASIN (Amazon Standard Identification Number) is a 10-character code of letters and digits that Amazon assigns to every product in its catalog. It uniquely identifies one product on Amazon and appears in the product's URL and in the product information section of the listing.

What does ASIN stand for?

ASIN stands for Amazon Standard Identification Number. Amazon created it as its own internal product identifier so every catalog item has a single, consistent reference regardless of which seller offers it.

Where do I find a product's ASIN?

The fastest way is the product URL: the 10-character code right after /dp/ or /gp/product/ is the ASIN. You can also scroll to the "Product information" or "Additional information" table on the listing, where the ASIN is listed as its own row.

Is an ASIN the same as a UPC?

No. A UPC is a global barcode standard used across all retailers and is owned by GS1. An ASIN is internal to Amazon only. For most non-book products a seller supplies a UPC or other GTIN when creating a listing, and Amazon then generates the ASIN for that listing.

Can two products share the same ASIN?

They should not. One ASIN is meant to represent one distinct product, and every seller offering that exact product lists against the same ASIN. Duplicate ASINs for the same item split reviews and sales history and usually need to be merged; different variations each get their own child ASIN under a parent.

How do I get an ASIN for a new product?

You do not request an ASIN directly. When you create a new listing in Seller Central with a valid product identifier (UPC, EAN, or GTIN exemption), Amazon assigns the ASIN automatically. Books use their ISBN-10 as the ASIN.