GS1 barcodes explained
The bars are free to draw. The number inside a retail barcode is not: it has to come from GS1, so that no two products on Earth share one. Here's how that works and when it matters to you.
Who GS1 is
GS1 is a not-for-profit standards body with member organisations in over 100 countries (GS1 US, GS1 UK, GS1 India and so on). It maintains the numbering system behind UPC and EAN barcodes, plus the rules for how they are printed. Its members include most major retailers, which is why its numbers are the ticket into their shops.
How a GTIN is built
- GS1 prefix: identifies the GS1 office that issued the company prefix (50 = GS1 UK). It says nothing about where the product was made.
- Company prefix: licensed to you. Its length sets how many products you can number: a longer prefix leaves fewer digits for items.
- Item reference: you assign one per product variant (each size, colour and pack count needs its own GTIN).
- Check digit: calculated from the rest. Try it in the check digit calculator.
The same GTIN can be printed as UPC-A (12 digits, North America) or EAN-13 (13 digits, a leading 0 added); scanners everywhere read both. Cartons use a GTIN-14 in ITF-14, and pallets an 18-digit SSCC in GS1-128.
When you need GS1 numbers, and when you don't
| Situation | GS1 number needed? |
|---|---|
| Selling in supermarkets or chain stores | Yes |
| Listing new products on Amazon and similar marketplaces | Usually yes (some offer exemptions for brand owners) |
| Books | No: use an ISBN from your ISBN agency |
| Your own shop's point of sale only | No: internal codes or Code 128 are fine |
| Warehouse bins, assets, library items, tickets | No |
| Medicines and medical devices | Yes, GS1 DataMatrix / UDI rules apply |
Prices and prefix sizes differ by country; check your national GS1 office's site. Once you have numbers, the barcode generator or bulk generator will draw them for free.
Ask about your product
Tell the advisor what you're selling and where. It points you to the right barcode and flags whether GS1 numbers are required. Treat it as a starting point and confirm with GS1 or the retailer.
Questions
What is a GS1 barcode?
A barcode that carries a GS1 identification number, usually a GTIN, in a GS1-approved symbology such as EAN-13, UPC-A, ITF-14, GS1-128 or GS1 DataMatrix. GS1 is the non-profit that manages these numbers worldwide.
Do I need GS1 barcodes?
You need GS1-issued numbers to sell through most supermarkets, chain stores and marketplaces that require GTINs (Amazon, for example, checks them against the GS1 database). You do not need them for internal inventory, asset tracking, event tickets or your own shop’s till.
Can I buy cheap barcodes from resellers?
Resellers sell numbers originally licensed to another company. The GS1 database will show that company, not you, and many retailers and Amazon reject them. GS1 recommends licensing directly from your national GS1 office.
Is the barcode image included when I license GS1 numbers?
GS1 licenses the numbers. You can create the barcode images yourself, for example with our generator, as long as they meet size and quality specifications.