GS1

GS1 – the barcode, the GTIN and the numbers behind every item

What do the numbers in a barcode mean? A walk through the GS1 standards – how a GTIN is built up, how the check digit is calculated, what the prefix actually says about country of origin, the keys beyond GTIN, and the move to 2D codes towards 2027.

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What this covers

What GS1 is, and why it exists
How a GTIN is built up, digit by digit
The check digit – and how to work it out yourself
The country myth – what the first digits actually mean
The GTIN family – 8, 12, 13 and 14 digits
The keys beyond GTIN – GLN, SSCC and the others
The symbologies – EAN-13, ITF-14, GS1-128, DataMatrix

What this covers (cont.)

Application Identifiers – what makes the logistics label powerful
Sunrise 2027 and the move to 2D
The link to RFID

Why it exists

From patent to global standard

1952The patent

1974First scan in a shop

2005GS1 is formed

An ideaAn agreement the world uses

More than twenty years passed between the patent and the first scan. What was missing was not the technology – that existed – but agreement on what the numbers should mean. American UPC came first, European EAN followed in 1977, and the two were merged into GS1 in 2005.

How the number is built up

The central concept is the GTIN – Global Trade Item Number. That is the number. The barcode is only one of several ways to carry it.

7001234567898, taken apart

700 — GS1 prefixSays which GS1 organisation allocated the prefix. 700–709 belong to GS1 Norway.
…1234 — company prefixAllocated to the business by GS1. The prefix is shorter for a business that needs many item numbers, and longer for one that needs few.
…56789 — item referenceThis the business decides entirely on its own. GS1 has no involvement in which item gets which number.
8 — check digitCalculated from the twelve preceding digits. Catches most scanning and typing errors.

Note how the lengths of the company prefix and the item reference vary inversely: a short company prefix leaves room for many items, a long one for few. That is why you cannot read out of the code where one ends and the other begins – only whoever allocated the prefix knows.

The same thirteen digits, cut two ways

Many products

Short company prefix

Fewer digits go to identifying the company
More digits are left for item references
Room for tens of thousands of products

Few products

Long company prefix

More digits go to the company
Fewer digits are left for item references
Room for a few hundred products

Thirteen digits are always thirteen. What moves is the boundary between the company and the item – and that boundary is not visible in the code. This is why you cannot tell from a GTIN where the company prefix ends without looking it up with GS1.

The check digit

You can work this out yourself, and it is worth being able to: it exposes a mistyped code in seconds.

Multiply the digits alternately by 3 and 1 from the right, add them up, and see how far it is to the next ten.

700123456789 → from the right: 9×3 + 8×1 + 7×3 + 6×1 + 5×3 + 4×1 + 3×3 + 2×1 + 1×3 + 0×1 + 0×3 + 7×1 = 27+8+21+6+15+4+9+2+3+0+0+7 = 102. The next ten is 110, and the difference is 8. The full code becomes 7001234567898. If the sum already lands on a ten, the check digit is 0.

Try the rule on a real product, and you will see that it holds.

7038010068980 is an ordinary grocery code. The body is 703801006898, and from the right that gives 8×3 + 9×1 + 8×3 + 6×1 + 0×3 + 0×1 + 1×3 + 0×1 + 8×3 + 3×1 + 0×3 + 7×1 = 24+9+24+6+0+0+3+0+24+3+0+7 = 100. Here the sum lands on a multiple of ten by itself, so the check digit is 0 – which is exactly what sits at the end of the code.

The country myth

This is the widespread misunderstanding, and it turns up in purchasing, in marketing and in consumer debate at regular intervals.

The prefix shows which GS1 organisation the company is registered with. It says nothing about where the item was made.

Why it goes wrong: a Norwegian company with a prefix in the 700 series can have its goods made in China, Poland or Italy – the code is the same. And a foreign company can sell an item made in Norway under its own prefix. GS1 states this explicitly itself: the prefix does not identify country of origin. To know where something was made, look at the origin marking, not at the barcode.

The GTIN family

Four lengths, four uses

Key	Digits	Used on
GTIN-13	13	The standard in Europe. The code you see on nearly everything in a shop. Carried by EAN-13.
GTIN-12	12	The American UPC form. Still common in North America.
GTIN-8	8	Small packs with no room for a full code – chewing gum, cosmetics.
GTIN-14	14	Outer packaging and cases. The first digit indicates which packaging level it is.

All four are the same kind of key, and systems often store them padded to fourteen digits with leading zeros. Worth knowing when two systems cannot find each other's items: often it is only the padding that differs.

The keys beyond GTIN

A GTIN identifies an item. GS1 has keys for the other things you need to point at, and the first two here are the ones actually used most in logistics.

The keys you will meet

Key	Identifies	Typical use
GLN	A place or a party	Warehouse, shop, department, legal entity. Used in EDI messages to say who and where.
SSCC	One particular shipping unit	Eighteen digits on the pallet label. Every pallet is unique, even if the contents are identical.
GRAI	Returnable transport item	Pallets, crates, cages – packaging that comes back.
GIAI	An individual asset	Tools, machines, IT equipment to be followed over time.

The SSCC is what makes tracing possible in practice. A GTIN says “this is a carton of milk”, while an SSCC says “this is exactly this pallet, dispatched on this day, from this warehouse” – and the latter is what you need when something has to be recalled.

The symbologies

Barcode is not one thing. Which pattern is used depends on where the code is to be read and how much it has to carry.

Which code where

Symbology	Carries	Where it is used
EAN-13 / UPC-A	A GTIN and nothing else	The retail checkout. Built to be read fast and reliably, and for no more than that.
EAN-8 / UPC-E	A short GTIN	Small packs.
ITF-14	A GTIN-14	Corrugated board and cases, where the print is coarse and the bars have to be robust.
GS1-128	Several pieces of data at once	The logistics label on the pallet: SSCC, GTIN, batch, date, quantity.
GS1 DataBar	A GTIN plus a little more	Fresh food and coupons, where date and weight have to fit in a small space.
GS1 DataMatrix	A great deal, on a very small area	Medicines and medical devices, where serial number and expiry date are required.
QR with GS1 Digital Link	All of the above, plus a web address	What is now arriving on consumer packaging.

Note the first row. EAN-13 can only carry the item number – no date, no batch, no serial. That is why a recall cannot be managed from the shop checkout alone, and why logistics needs GS1-128.

Application Identifiers

This is the mechanism that makes a GS1-128 label machine-readable without any prior agreement, and it is simpler than it looks.

Each field is introduced by a code in brackets saying what the next number means.

(01) 07001234567898 (10) A4472 (17) 271231 reads as: the item is GTIN 07001234567898, batch A4472, best before 31 December 2027. (00) is the SSCC, (21) is a serial number, (37) is a quantity. The brackets are printed for the human eye – in the barcode itself there is a separator character instead.

Sunrise 2027

GS1 is now running a global move from 1D to 2D. The aim is for retail checkouts to be able to read both traditional barcodes and GS1-approved 2D codes by the end of 2027 – in practice GS1 DataMatrix and QR with GS1 Digital Link.

The link to RFID

What is worth taking with you

Key points

GS1 allocates the company prefix. The business creates the item numbers itself.
The check digit is simple arithmetic, and you can work it out in your head.
The prefix shows where the company is registered, not where the item was made.
The GTIN is the number. The barcode is only one of several ways to carry it.

Key points (cont.)

GS1-128 and Application Identifiers are what make a logistics label machine-readable.
An SSCC identifies the individual pallet, a GLN identifies the place.
The aim of Sunrise 2027 is for the checkout to be able to read both 1D and 2D.
The number on an RFID tag is built on the same keys.

Questions this answers

What is GS1, and what does the organisation do?
What do the numbers in a barcode mean?
How do you work out the check digit?
Can you tell which country an item was made in from its barcode?
What is the difference between GTIN-8, GTIN-12, GTIN-13 and GTIN-14?
What are GLN and SSCC?

Questions this answers (cont.)

Which barcode types exist, and where is each used?
What are Application Identifiers?
What is Sunrise 2027?
How do GS1 and RFID fit together?

Sources

GS1 – GS1 General Specifications and the identification key standards
GS1 – Company Prefix and the prefix list for member organisations
GS1 – 2D barcodes and Sunrise 2027

Spørretimen

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