SKU, barcode, GTIN: which do you need?
These three words get used as if they mean the same thing, and the confusion costs money — usually when a pallet of printed packaging turns out to carry a number that belongs to someone else. They describe three different things: a name you choose, a way of printing it, and a number issued to you.
A SKU is yours and means nothing outside your business
A stock keeping unit is your own identifier for a product: TSHIRT-BLK-M, or 10442. You invent it, you decide the format, and it only has to be unique within your own system. Nobody else needs to recognise it, which is exactly why it is the right thing to put on internal stock, shelves, bins and asset tags. Make it readable to a human as well as a scanner, keep the length steady so barcodes stay a predictable width, and avoid characters that are easy to confuse when someone reads one out.
A barcode is a way of printing a number, not the number itself
"I need a barcode" usually means "I need a number and a way to print it". The barcode is only the printing part — Code 128, EAN-13 and the rest are just alphabets for machines. Any of them will happily encode any number, valid or not. That is what makes this confusing: a tool can draw you a perfect, scannable EAN-13 of a number you invented, and it will scan, and it will still be wrong in a shop, because scanning is not the same as being registered.
A GTIN is issued to you, and that is the part we cannot supply
A Global Trade Item Number is the number behind a retail barcode, and the ranges are issued by GS1, the organisation that administers them, to the company that owns the product. That is what makes a retailer's system able to say which company and which product a number refers to. If you are going to sell through shops or most large marketplaces, you get your number from GS1 in your country — it is a paid registration, not a calculation. This app draws barcodes; it does not and cannot issue you a GTIN, and any tool that offers to generate a "free GTIN" is either giving you an internal-use range or giving you a number that belongs to somebody else.
So what should you actually do
If the label never leaves your own operation — warehouse, workshop, office, market stall where you ring up sales yourself — invent a SKU and print it as Code 128. It costs nothing and works perfectly. If the product will be scanned at somebody else's till or listed on a marketplace that requires it, register with GS1, get your numbers, then use this app to lay out the label properly. And if you are re-selling someone else's product, do not create a number at all: the manufacturer's existing barcode is the correct one to use.
Frequently asked questions
Can I create my own barcode for free?
You can create the barcode, yes, and for internal stock that is completely legitimate. What you cannot create for free is a GTIN for retail sale — that number has to be issued to you by GS1.
What is the difference between a SKU and a barcode?
A SKU is an identifier you invent for your own use. A barcode is a way of printing an identifier so a machine can read it. You can print a SKU as a barcode; that does not make it a retail product number.
Do I need a GTIN to sell on a marketplace?
Many large marketplaces require one, some grant exemptions for handmade or own-brand goods. Check the rules of the specific marketplace before buying numbers.
Are the cheap barcode numbers sold online legitimate?
Be careful. Some are resold from ranges issued before the rules changed, and retailers and marketplaces increasingly check that the number resolves to the company selling the item. If it must be right, register directly.
I am reselling a product that already has a barcode.
Use the manufacturer's barcode. Creating a second number for the same product causes exactly the confusion the system is designed to prevent.
What should I use for asset tags and shelf labels?
Your own code in Code 128. Nothing external needs to recognise it, so no registration is involved.
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