SKU vs product ID vs barcode: what is the difference?
Three terms sellers mix up. A plain-language explanation of what a SKU, a product ID and a barcode each are and who uses them.
If you have ever filled in a courier form, a marketplace listing or an inventory sheet, you have met all three of these terms. They sound similar and are often used interchangeably, but they do different jobs. Here is each in plain language.
SKU: your own label
A SKU, or stock keeping unit, is a code you choose to name one exact sellable item, such as the olive kurta in size M. It is yours: you decide the format, and it only needs to make sense inside your business. Its purpose is to help you pick, pack and count correctly. A readable pattern is covered in how to set up SKU codes for a small store.
Think of it as the name you write on the box.
Product ID: a system label
A product ID is a code that a piece of software generates and uses internally to tell records apart. It is usually a long mix of letters and numbers that no human would choose. You rarely type it; the system uses it to link an order to a product, or a photo to a listing.
For example, the shipping integration on a Varchas store builds an identifier for each item from part of the product's internal ID plus the colour and size, because the product editor itself does not ask you for a separate SKU. That identifier is made for the courier flow and is not something you need to set up. The point is that an ID like this exists for the system's benefit, not for yours.
Think of it as the number a database uses to find a row.
Barcode: a machine-readable image
A barcode is a picture of lines or squares that a scanner can read quickly. It encodes a number or text. It does not mean anything on its own; the meaning comes from what number is stored inside it and what system looks it up.
Barcodes can encode many things: your own SKU, a standard product number or an order number. There are different types, and rules about standardised product numbers can apply in some situations. I am not stating any current requirement here; check with an official source or a professional if a retailer, marketplace or courier asks you for one.
Think of it as a way to read a code without typing.
How the three fit together
Here is one item, seen three ways:
- SKU: KUR-BLOCK-OLV-M, chosen by you
- Product ID: a long system-generated string, created by software
- Barcode: a printed image that can encode either of those, or something else
The SKU is for people in your business, the product ID is for software, and the barcode is for scanners.
Do you need all three?
For a small online seller:
- A SKU is helpful once you have many colours and sizes.
- A product ID comes automatically with whatever software you use.
- A barcode is only needed if someone asks for it or you start scanning stock.
Do not rush to create all three. Start with clear product names, add SKUs if your stock gets confusing, and think about barcodes later. For naming patterns, see SKU naming convention examples.
A simple takeaway
When someone asks "what is the SKU?", they want your own short code for that exact variant. When they ask for the product ID, they mean the system's reference. And when they ask for the barcode, they want something a scanner can read.