This page covers the four questions we hear most often. Each answer links to a detailed guide if you need more depth.
Do I need to join GS1?
Not necessarily. GS1 is the standards body that manages the global GTIN system. They issue new company prefixes to members who join their organization. Membership gives you a prefix to create your own numbers and access to their data pools. Numbers you create will be associated with your business in GS1’s databases.
Many small and medium businesses buy individual GTINs through barcode resellers instead. These are legitimate numbers that work for most retailers and online platforms, though a minority of chains (notably some large grocery and pharmacy retailers, and Amazon) require direct GS1 membership.
See Do I need GS1? for retailer-specific requirements and how to decide.
EAN vs UPC: what’s the difference?
| Feature | UPC-A | EAN-13 |
|---|---|---|
| Digits | 12 | 13 |
| Common in | USA, Canada | Rest of world |
| Compatibility | Scannable globally | Scannable globally |
| Relationship | EAN-13 contains UPC-A (with leading zero) | EAN-13 is a superset that contains UPC-A |
Both barcode symbologies, EAN-13 and UPC-A, encode GTINs. A UPC-A is essentially an EAN-13 with a leading zero. Modern scanners read both formats worldwide, so the “vs” matters more for retailer data systems than physical scanning. UPCs are still preferred for US brick-and-mortar; EAN-13 is the default everywhere else.
More detail: EAN vs UPC
How many barcodes do I need?
One unique barcode per product variation:
- Different sizes (e.g. 250ml vs 500ml)
- Different colours or flavours
- Different packaging types (single vs multipack)
Same barcode for:
- Identical products even if they are in different batches or production runs
- Same item sold through different channels (unless the retailer requires channel-specific codes)
If you sell 5 flavours in 2 sizes each, you need 10 barcodes minimum.
Full breakdown with examples: How many barcodes do I need?
Why won’t my barcode scan?
Common causes in order of frequency:
| Issue | Quick check |
|---|---|
| Poor print quality / low resolution | Minimum 300 DPI for offset, higher for small labels |
| Insufficient quiet zone | Clear space required left and right of bars |
| Wrong colours | Dark bars on light background; red bars fail |
| Damaged or wrinkled label | Physical inspection |
| Incorrect check digit | Validate with GTIN check digit calculator |
| Wrong barcode type for the application | EAN-13 for retail, Code 128 for internal use, etc. |
GS1 publishes detailed guidance on print quality and verification in GS1 UK: Barcoding — Getting It Right.
Step-by-step troubleshooting: Barcode won’t scan
Further reading
- GS1 GTIN standards
- GS1 US: What is a GTIN?
- International Barcodes Network — 120+ member reseller sites worldwide with local support