what’s the difference between an ASIN and my own SKU?
Hey guys, I’ve been selling on Amazon for about 6 months now, and I keep running into all these codes – ASIN, FNSKU, SKU, UPC… It's getting a little overwhelming. I get that they’re all some kind of identifiers, but when it comes to practical use, I feel like I’m mixing them up constantly. Like, when do I actually need a UPC versus an FNSKU? And what’s the difference between an ASIN and my own SKU? Would love to hear how others are managing this or if you have any clear examples to break it down.
Discussion
Since then, I keep a little chart near my desk just to be safe. It's a bit confusing at first, but once it clicks, it makes managing inventory a lot smoother.
When I started, it took me weeks to sort it out, and honestly, I still double-check sometimes. Think of it like this: the ASIN is Amazon’s catalog number – each product on Amazon has one. If you’re reselling something already on Amazon, you’ll use its existing ASIN. Your SKU is whatever you want it to be – it’s internal, just for your own tracking. You can make it say “RED-TSHIRT-MEDIUM” or whatever helps you identify it. Now, the UPC is a universal barcode – it comes from GS1 or wherever you bought it – and Amazon usually wants this when you’re creating a brand new listing. The FNSKU is where it gets Amazon-specific again – if you’re using FBA, this is the barcode they want on the label.
There’s a pretty decent breakdown here if you want it laid out visually asin vs upc asin vs upc : https://eboostpartners.com/what-are-amazon-asin-sku-fnsku-and-upc/
That page helped me understand which code is for what stage. I actually bookmarked it back when I was setting up my first private label product. It’s worth skimming even if you’re not doing FBA yet – saves some future headaches.