An ASIN (Amazon Standard Identification Number) is the unique 10-character code Amazon gives every product in its catalog. It is made of letters and numbers and usually starts with “B0”, for example B0 followed by eight more characters. Books are the exception: their ASIN is normally the same as the 10-digit ISBN. Amazon uses the ASIN to identify the product page, so every seller offering the same product shares one ASIN.
This guide explains what an ASIN is, where to find it, how it differs from a SKU, UPC and FNSKU, and what sellers need to know when they list products. The definition and lookup steps follow Amazon’s own guide, What is an ASIN?, checked on November 11, 2026.
What does ASIN mean?
ASIN stands for Amazon Standard Identification Number. It works like a catalog number inside Amazon:
- One product page, one ASIN. The ASIN belongs to the product detail page, not to the seller.
- Many sellers can share it. When several sellers offer the same item, they all list under the same ASIN and compete for the Featured Offer (the Buy Box).
- It is used only on Amazon. Outside Amazon, products are identified by barcodes such as UPC or EAN.
How to find an ASIN number
- In the product page URL. Look for the 10 characters right after “/dp/” in the address bar.
- In the product details. Scroll down the product page to the “Product information” or “Product details” section, where the ASIN is listed.
- In Seller Central. For your own listings, open Manage All Inventory. The ASIN appears next to each product.
- In your reports. Inventory, order and fee reports include an ASIN column, which is the easiest way to pull many ASINs at once.
An “ASIN lookup” simply means pasting an ASIN into the Amazon search bar, or after “/dp/” in an Amazon URL, to open that product page.
ASIN vs SKU vs UPC vs FNSKU
| Code | Who creates it | What it identifies | Where it is used |
|---|---|---|---|
| ASIN | Amazon | A product page in Amazon’s catalog | Amazon only |
| SKU | You, the seller | A product in your own inventory | Your systems and every channel you sell on |
| UPC / EAN (GTIN) | GS1, through the brand owner | A product worldwide, printed as a barcode | Retail stores and all marketplaces |
| FNSKU | Amazon | Your units of a product in Amazon’s warehouses | FBA labels and shipments |
In short: the UPC says what the product is everywhere, the ASIN says which Amazon page it lives on, the SKU is your own name for it, and the FNSKU ties physical FBA units to you. See our FNSKU labeling guide for the FBA side.
How sellers get an ASIN
Match an existing ASIN
If the product is already in Amazon’s catalog, you add your offer to the existing page. You enter your price, condition, quantity and fulfillment method, and your offer appears under the same ASIN as other sellers.
Create a new ASIN
If the product is new to Amazon, you create a new product detail page and Amazon assigns a new ASIN. Amazon normally asks for a product ID such as a UPC or EAN to do this. Brands without barcodes, such as private label or handmade sellers, can apply for a GTIN exemption.
Parent and child ASINs
Products that come in sizes or colors use a variation family. Each size and color combination is a child ASIN that customers can buy, and a parent ASIN groups them on one page. The parent itself cannot be purchased.
Common ASIN mistakes
- Creating a duplicate ASIN for a product that already has a page. Amazon’s policy is one page per product, and duplicates can be merged or removed.
- Listing on the wrong ASIN, for example a different pack size or version. This leads to “not as described” returns and complaints.
- Confusing ASIN and SKU. You can change how you organise SKUs, but you cannot choose or edit an ASIN.
- Tracking by ASIN only. ASINs exist only on Amazon, so they cannot connect the same product on Walmart, eBay or your own store.
Using ASINs when you sell on more than one channel
Each marketplace has its own identifier: Amazon uses ASINs, Walmart uses item IDs, eBay uses item numbers. The code that links them is your own SKU. Crazy Vendor’s multichannel listings map each product’s ASIN to the matching listing on Walmart, eBay, Etsy and Shopify under one SKU, so inventory stays in sync and one sale updates every channel. Plans start at $29/month with a 21-day free trial. See pricing.
Related: how to start Amazon FBA and Amazon FBA fees 2027.
Frequently asked questions
What is an ASIN number?
It is the Amazon Standard Identification Number, a unique 10-character code of letters and numbers that Amazon assigns to each product in its catalog.
Where do I find the ASIN on Amazon?
In the product page URL right after “/dp/”, or in the Product information section lower on the page. Sellers also see it in Manage All Inventory in Seller Central.
Is an ASIN the same as a UPC?
No. A UPC is a global barcode issued through GS1 and used by every retailer. An ASIN is Amazon’s own catalog code and is used only on Amazon.
Is an ASIN the same as a SKU?
No. Amazon assigns the ASIN and it is the same for every seller of that product. A SKU is a code you create for your own inventory.
Do books have ASINs?
Yes. For books with a 10-digit ISBN, the ASIN is normally the same as that ISBN, which is why book ASINs begin with a number rather than “B0”.
Last checked against Amazon’s seller resources on November 11, 2026.