UPC and EAN barcodes: what the digits say

Nearly every book, comic, film and game made since the 1980s has a barcode on it somewhere: the back of a DVD case, the cover of a comic, the back of a book, the bottom of a game box. The bars are for a till, but the digits under them are for you. They say who registered the product, they catch typing mistakes, and the small extra barcode beside them can tell one printing or issue from the next.

UPC and EAN are one system

The barcode Americans call a UPC was adopted by the US grocery trade in 1973. A few years later Europe extended it by one digit and called it EAN, and the two bodies that ran them later merged into the organisation now called GS1.

• UPC-A has 12 digits. It is the usual barcode in the US and Canada. The digits are printed in two groups of five, with a single digit at each end, outside the bars.
• EAN-13 has 13 digits. It is the usual barcode everywhere else, and its digits are printed as one digit followed by two groups of six.

Every UPC is an EAN with a 0 in front. The bars of a UPC and of an EAN starting with 0 are exactly the same, so a scanner can't tell them apart and may report either 12 digits or 13. Many phone scanning apps add the 0 to everything. When you record a barcode, copy the digits printed under the bars, not what an app reports.

Japan uses EAN-13 under the name JAN, with prefixes starting 45 or 49.

What the digits mean

An EAN-13 reads in four parts.

1. The GS1 prefix, the first two or three digits. It says which national GS1 office handed out the company's number, not where the product was made. 500 to 509 is Britain, 400 to 440 Germany, 300 to 379 France, and most of 000 to 139 the US and Canada. A few prefixes are not countries at all: 978 and 979 mean a book, and 977 a magazine or other serial.
2. The company number, assigned by GS1. Its length varies: a big company gets a short one and more room for products.
3. The item number, which the company assigns to each product.
4. The check digit, the last one, worked out from the other twelve.

For a UPC, put a 0 in front and read it the same way. The Marvel UPC 7 59606 08372 5 becomes 0759606083725, and its prefix 075 is in the US and Canada range.

There is no central list that turns a barcode into a product. GS1 knows which company owns a number, but what each item number means is up to the company.

Checking the check digit

The check digit catches most typing mistakes, so it is worth knowing how to test one. For an EAN-13, take the first twelve digits. Multiply them by 1 and 3 in turn, starting with 1. Add the results. The check digit is whatever takes that total up to the next multiple of 10.

The barcode on The Complete Calvin and Hobbes is 978074074847, then a check digit:

The results add up to 131. The next multiple of 10 is 140, so the check digit is 9, and the barcode reads 9780740748479.

For a 12-digit UPC, the weights start with 3 instead: 3, 1, 3, 1 and so on for the first eleven digits. For 7 59606 08372 that gives 95, so the check digit is 5. If a code you have typed fails this test, one of the digits is wrong, or the code was misprinted.

Books: ISBNs in the bars

A book's barcode is its ISBN. To make a barcode from an old ten-digit ISBN, put 978 in front, drop the last character, and work out a new check digit. The Calvin and Hobbes set has ISBN 0-7407-4847-5 on its copyright page, and 9780740748479 under its bars: the same nine digits in the middle, with a different check digit at each end, because ISBN-10 and EAN use different sums. Since 2007 the ISBN itself has had thirteen digits and matches the barcode exactly. Some countries now issue ISBNs starting 979, which have no ten-digit form.

ISBN, SBN, LCCN and the other numbers in a book covers the book codes in full.

The add-on: the small barcode beside it

Some barcodes have a second, shorter one to the right, with its digits printed above the bars. This add-on holds 2 or 5 digits and is part of the same barcode. Many shop scanners ignore it. It is not a code on its own and means nothing without the barcode it sits beside.

• On books and trade paperbacks the 5 digits are the price. A first digit of 5 means US dollars: the trade paperback of Darth Maul has 51699 beside its barcode and $16.99 on its cover. 90000 means no price is coded.
• On American comics the 5 digits give the issue number, the cover and the printing. Volume, issue and collected volume shows how to read them.
• On magazines a 2-digit add-on usually gives the issue number.

Because the add-on changes when the price, the issue or the printing does, it is often the quickest way to tell two otherwise identical items apart.

Barcodes that are wrong

Barcodes are printed by people, and mistakes happen. A barcode can fail its check digit, scan as something else, or belong to a different product. Sometimes the digits printed under the bars don't match the bars. Bootlegs often carry a copied or made-up barcode on purpose. Record what is printed, and if you notice a problem, say so in the notes rather than correcting it silently.

Never copy a barcode from another edition because yours "should" have the same one. A missing or different barcode is one of the facts that tells editions apart.

Where barcodes go on ctlgs

Every catalog that takes a barcode puts it under Identifying Codes, one row per code, with the digits copied as printed, spaces included.

• Books. Choose "Barcode (EAN)" for 13 digits and "Barcode (UPC)" for 12. Put a 5-digit add-on in its own row straight after it, as "EAN 5" or "UPC 5".
• Comics. Choose "UPC" or "EAN". On a modern American issue, enter the UPC and its add-on together in one row, so each issue gets its own code. Put the ISBN of a trade in its own row as "ISBN".
• Home video. The type is typed in rather than picked; use "Barcode", which is what most releases have. Codes molded in the clear ring at the centre of a disc are a different thing: DVD codes explained covers them.
• Video games. Choose "Barcode", on a release or a piece of hardware. Codes in a disc's ring go in as "Disc Ring Code".

Gig posters, hi-fi and music gear have no barcode field. A poster rarely has one, and a gear entry describes the model rather than the box it came in. If a box barcode is the only way to tell two versions apart, mention it in the entry's notes.