THE BARS
Widths that spell digits
A linear barcode encodes the product's GTIN, its Global Trade Item Number, using a series of lines and spaces of different widths.
Check a numberHOW BARCODES WORK
Beep: a number
in bars.
A barcode is a number, written in bars.
Check a number
13 DIGITSone is a check
The stripes on a packet spell out a product number, the GTIN, in lines and spaces of different widths. A scan links the physical product to its digital record. The last digit is a check calculated from the others.
At a glance
- Bars encode digits
- The last digit checks
- The scan links to the record
- The everyday barcode
1 billion+
Products carrying GS1 barcodes
GS1 says over a billion products now carry its barcodes, scanned billions of times every day around the world.
PRODUCTS · GS1
116
Local GS1 member organisations
The system is run through 116 local GS1 member organisations. Company prefixes 500 to 509 are managed by GS1 UK.
ORGANISATIONS · GS1
TWO NUMBERS WORTH KNOWING
Fifty years,
billions of beeps.
Figures from GS1 for the barcode's
50th anniversary in 2024.
GS1 is now moving towards 2D codes, including QR codes using its Digital Link standard, which can hold more data than a linear barcode while appearing smaller.
CHECK A NUMBER
Work out the
check digit.
GS1's own worked example for a 13-digit GTIN. Pick a step to follow it. The bar shows how far through the calculation you are.
Worked example from GS1, How to calculate a check digit manually.
THE SHORT ANSWER
Stripes in,
number out.
Linear barcodes use variable-width
lines and spaces to encode data.
THE SCAN
Laser or camera
Barcodes are read by laser or image-based scanners. GS1, which runs the system, recommends scanners with imaging capability.
See the numbers
THE FIRST BEEP
Ohio, 26 June 1974
A pack of chewing gum at a supermarket in Ohio became the first product ever scanned with a barcode at a checkout.
How it began
A SHORT HISTORY
From grocery idea
to global code.
The barcode on almost every packet started as an agreement in the US grocery trade.
3 April 1973
Leaders in the US retail grocery sector agree the barcode, the Universal Product Code.
An administrator appointed
The US-based Uniform Code Council is appointed to run the new Universal Product Code.
26 June 1974
A pack of chewing gum is scanned at a supermarket in Ohio, the first product in the world scanned with a barcode.
50 years on
GS1 marks the anniversary in 2024 and promotes next-generation 2D barcodes, including QR codes.
WHY A CHECK DIGIT
One digit
guards the rest.
The final digit is calculated from all the others using a fixed rule. That means a number with a wrong digit will usually no longer add up, which is what a check digit is for.
GS1 publishes the same multiply-by-three-and-one method for its 8, 12, 13, 14, 17 and 18-digit keys, so one simple rule protects product numbers and shipping labels alike.
Questions
Questions people ask
What does a product barcode contain?
An identification number. Linear barcodes on consumer goods encode the GTIN for product identification, and a scan connects the physical product to its digital information.
How is the check digit calculated?
Multiply each digit by 1 or 3 in turn, add the results, then subtract the total from the next equal or higher multiple of ten. In GS1's example the sum is 57, so the check digit is 3.
What does 50 at the start mean?
In the GS1 Company Prefix list, prefixes 500 to 509 are managed by GS1 UK.
When was the first barcode scanned?
On 26 June 1974, at a supermarket in Ohio, USA, when a pack of chewing gum was scanned at the checkout.
What is the difference between a barcode and a QR code?
A linear barcode uses lines and spaces. 2D codes such as QR codes use patterns of squares, dots or other shapes, so they can hold more data in less space.
Sources
Where the facts come from
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