EAN vs UPC vs GTIN vs ISBN: the differences explained

GTIN is the umbrella term for every barcode product number, and EAN and UPC are two lengths of it: an EAN-13 is a 13-digit GTIN (GTIN-13), used mainly outside North America, and a UPC-A is a 12-digit GTIN (GTIN-12), used mainly in the US and Canada. Add a leading zero to a UPC and it becomes a valid EAN-13, so the two systems are compatible rather than competing.

The rest of the family follows the same logic. GTIN-8 (EAN-8) is a short version for very small packs, GTIN-14 identifies cartons and outer cases, and ISBN and ISSN are book and magazine numbers that sit inside the GTIN system under their own prefixes (978–979 and 977). Identifiers such as ASIN, FNSKU, SKU and MPN look similar on a product sheet, but they are not GTINs at all.

This guide explains each identifier, how they convert into one another, which one a marketplace or feed field is really asking for, and the mix-ups that cause most listing errors. If you are completely new to product codes, start with our guide what an EAN code is and how online sellers use it, then come back here for the differences.

What is a GTIN? The umbrella term behind every product barcode

GTIN stands for Global Trade Item Number. It is the name GS1, the global standards organisation behind retail barcodes, uses for its item identifiers. A GTIN identifies one specific trade item: one product in one size, colour, flavour and pack. It says nothing about price, stock or where the item was made. Retailers and marketplaces use it as a key to look up everything else.

A GTIN comes in four lengths. Google's Merchant Center specification, one of the clearest public summaries, accepts exactly these four: 8, 12, 13 or 14 digits (Google Merchant Center: gtin).

• GTIN-8: 8 digits, carried in an EAN-8 barcode, for very small packs.
• GTIN-12: 12 digits, the number in a UPC-A barcode, used mainly in the US and Canada.
• GTIN-13: 13 digits, the number in an EAN-13 barcode, used in Europe and most of the rest of the world. Japan's JAN code is also a GTIN-13.
• GTIN-14: 14 digits, used for trade units such as cartons and outer cases, usually printed as an ITF-14 or GS1-128 barcode.

So "GTIN" is the family name and "EAN", "UPC", "JAN" and "ITF-14" are the everyday names for particular members. When a marketplace form asks for a "GTIN", any of the four lengths is technically a GTIN, although in practice a European consumer product will almost always use a 13-digit EAN.

Why the different lengths all fit together

The four lengths share one numbering logic. Every GTIN ends in a check digit calculated with the same mod-10 method, and any GTIN can be written as 14 digits by adding leading zeros. GS1 UK describes exactly this when it explains that a GTIN-13 needs a leading zero when it sits in a 14-digit field (GS1 UK: packaging levels). Leading zeros do not change the check digit, which is why a UPC, an EAN and a padded GTIN-14 can all point to the same product.

Written as	Example (illustrative)	Same item?
UPC-A (GTIN-12)	012345678905	Yes
EAN-13 (GTIN-13)	0012345678905	Yes, one leading zero added
14-digit field (GTIN-14 format)	00012345678905	Yes, two leading zeros added

The example number above is a common dummy used to illustrate the arithmetic. It is not presented as a real product.

EAN vs UPC: what is the difference?

The short answer: length and history. A UPC-A is 12 digits and an EAN-13 is 13 digits. Both are GTINs, both use the same check digit method, and the barcodes look almost identical: black and white bars with the digits printed underneath. Modern checkout scanners read both.

The longer answer goes back to how barcodes spread. The UPC (Universal Product Code) was the North American system, run by the organisation that is now GS1 US. The EAN (originally European Article Number) extended the idea to the rest of the world by adding one digit at the front. That extra digit gave room for more number ranges, which GS1 later divided between its national offices. The European name stuck even after the system went global: the EAN was renamed GTIN-13 in 2009, but nearly everyone still says "EAN" (Shopify).

	EAN-13	UPC-A
GTIN name	GTIN-13	GTIN-12
Digits	13	12
Main region	Europe and most of the world	US and Canada
First digits	2–3 digit GS1 prefix, then the rest of the company prefix	Company prefix starting with 0 or 1 (when written as EAN-13)
Check digit	Mod-10, weights 1 and 3	Mod-10, weights 1 and 3
Short version	EAN-8 (GTIN-8)	UPC-E (8 digits, compressed)
Nominal barcode size	About 37.29 × 25.93 mm	About 37.29 × 25.91 mm
Convert to the other	Only if it starts with 0: drop the leading 0	Always: add a leading 0

The nominal sizes come from a printer manufacturer's guide (idprt, a commercial source); our barcode printing guide covers size, quiet zones and colours in detail.

How to convert a UPC to an EAN (and back)

1. Take the 12-digit UPC-A, for example 012345678905.
2. Put a 0 in front of it: 0012345678905. That is now a valid 13-digit EAN.
3. Keep the last digit as it is. The check digit does not change, because a leading zero adds nothing to the weighted sum.
4. To go back, an EAN-13 that starts with 0 can be written as a UPC-A by removing that first 0. An EAN-13 starting with any other digit has no UPC-A equivalent.

This is also why codes from the US often appear in European systems starting with 0. If you see an EAN like 0xxxxxxxxxxxx, it is very likely a UPC-A written in 13-digit form. That tells you the company prefix was issued by GS1 US, nothing more.

What about UPC-E?

UPC-E is a compressed 8-digit form of certain UPC-A numbers, used on small packs in North America. It is not a separate number: it expands to a 12-digit UPC-A according to fixed rules. Google tells sellers to convert UPC-E codes to their 12-digit form before submitting them. Do not confuse UPC-E with EAN-8, which is its own 8-digit number with its own allocation.

Can I use a UPC in Europe, or an EAN in the US?

Yes. Because both are GTINs and modern scanners read both symbologies, a product with a UPC-A can be sold in Europe and a product with an EAN-13 can be sold in North America. Marketplaces generally accept either in the product ID field, as long as you pick the right type in the dropdown (choosing "EAN" and then pasting 12 digits is a common reason for rejection, see the mix-ups section below).

What matters for acceptance is not whether the code is called a UPC or an EAN, but whether it is valid, unique to the product, and, on channels that check it, licensed to the brand you are listing. The prefix itself is not a passport. A product with a code starting with 0 is not "American", and a product starting with 87 is not "Dutch".

GTIN vs EAN: are they the same thing?

Almost. Every EAN-13 is a GTIN, but not every GTIN is an EAN-13. "GTIN-13" and "EAN-13" refer to the same 13-digit number; GS1 prefers the GTIN name, while sellers, suppliers and many marketplaces still say EAN. If a supplier sends you an "EAN" and a form asks for a "GTIN", you can enter the EAN as it is.

The confusion usually comes the other way round. When an American form asks for a "GTIN" and you have a UPC, you enter the 12-digit UPC. When a European form asks for an "EAN" and you have a UPC, you enter it with a leading zero. When a logistics partner asks for the "GTIN of the carton", they mean a GTIN-14 for the outer case, not the EAN of the single item inside.

The anatomy of a GTIN-13

An EAN-13 has three parts (as GS1 Spain describes them):

• GS1 Company Prefix (7–10 digits): it starts with a 2–3 digit GS1 prefix that shows which national GS1 office issued it, followed by the rest of the company number.
• Item reference: the digits the brand owner assigns to individual products. The longer the company prefix, the fewer item references are left. GS1 Germany, for example, sells a 9-digit base number for 1,000 GTINs, an 8-digit one for 10,000 and a 7-digit one for 100,000.
• Check digit: the final digit, calculated from the first 12.

Take the illustrative number 8712345678906. The first 12 digits weighted alternately by 1 and 3 add up to 114; the next multiple of 10 is 120, so the check digit is 6. This shows the arithmetic only; it is not a real product. You can test any number with the calculator below or read the full method in our EAN check digit guide.

GTIN-8 and EAN-8: the short code for small packs

An EAN-8 carries an 8-digit GTIN-8. It exists for products that are too small for a full EAN-13 barcode: think lip balm, a small tube of glue or a single spice sachet. The barcode is roughly two thirds the width of an EAN-13.

GTIN-8 numbers are scarce because 8 digits allow far fewer combinations, so GS1 offices hand them out only when they are really needed. GS1 Netherlands, for instance, assigns an EAN-8 only for certain sizes, for example when the total printable area is under 80 cm², and points out that you can often shrink an EAN-13 instead. Prices reflect this: GS1 NL charges a one-off €53 for a GTIN-8, and GS1 Germany charges €16 a year for a short number.

Does an EAN-8 fit in a 13-digit field?

Yes, padded with zeros. An EAN-8 written to 13 digits gets five leading zeros, and to 14 digits it gets six. The check digit stays the same. Be careful, though: some systems treat a code starting with several zeros as a UPC. If a marketplace has a separate "EAN-8" or "GTIN" option, choose that rather than forcing the code into a UPC field.

Should a small online seller use EAN-8?

Usually not. Most sellers who ask about EAN-8 actually want a smaller barcode, not a different number. A standard EAN-13 can be printed down to about 80% of its nominal size, and on a small label that is often enough. GTIN-8 makes sense when the pack is genuinely tiny and a scanner at a till needs to read it; for online-only products it rarely adds anything.

GTIN-14 and ITF-14: codes for cartons and outer cases

A GTIN-14 identifies a trade unit rather than a consumer unit: a carton of 12 bottles, a case of 48 tins, an outer box of 6 inner packs. Warehouses and distribution centres scan these, not shoppers at a till. GTIN-14s are usually printed as an ITF-14 barcode (a chunky barcode often printed directly on corrugated cardboard) or inside a GS1-128 barcode on logistics labels.

GS1 UK draws a clear line: a retail consumer unit must carry a GTIN-13 in an EAN-13 barcode, while higher packaging levels can use GTIN-14. In a GTIN-14 field, a GTIN-13 is written with one leading zero.

How a GTIN-14 relates to the EAN of the single item

A carton is a different trade item from the unit inside it, so it needs a different number. One common way to build it is to take the 12 digits before the check digit of the item's GTIN-13, put a packaging-level digit in front and calculate a new check digit. Using the illustrative 8712345678906:

Level	Identifier	Number (illustrative)	Barcode
Single item (consumer unit)	GTIN-13	8712345678906	EAN-13
Same item in a 14-digit field	GTIN-13 padded	08712345678906	Used in data, not a new item
Carton of 12	GTIN-14	18712345678903	ITF-14 or GS1-128

Notice that the carton's check digit changes from 6 to 3, because the leading 1 is a real digit, not padding. Many brand owners simply assign a fresh GTIN-13 to their cartons instead; both approaches are used. Either way, the carton never shares a number with the unit.

Do marketplace sellers need GTIN-14?

Rarely. If you sell single items online, you need a GTIN for each sellable variant, not for the boxes your supplier ships them in. GTIN-14 becomes relevant when you supply wholesale, ship to retail distribution centres or sell fixed multipacks that a customer buys as a single unit. Google, for instance, accepts "ITF-14 (multipacks): 14 digits" in its gtin attribute. When a multipack is sold to consumers as one product, many sellers give it its own GTIN-13 instead. Our article on variants, bundles and when you need a new EAN walks through those decisions.

ISBN and ISSN: why books and magazines have their own numbers

An ISBN (International Standard Book Number) is a book identifier that has been folded into the GTIN system. Since books moved to 13-digit ISBNs, an ISBN-13 is also a valid GTIN-13. It starts with the GS1 "Bookland" prefix 978 or 979. Magazines and other serials use an ISSN, which goes into a GTIN-13 under prefix 977.

The crucial difference is who issues them. ISBNs come from national ISBN agencies, not from GS1 and not from barcode resellers. If you publish a book, you get the ISBN from the ISBN agency in your country and print it as an EAN-13 barcode on the cover. An ordinary EAN from a product code supplier is the wrong identifier for a book, and you should not use one.

One ISBN per edition

Each format and edition of a book is a separate product: the hardcover, the paperback and the e-book each need their own ISBN. bol.com spells this out for its sellers (bol.com partner platform). A revised second edition also gets a new number, which matches the general rule that a changed product needs a new identifier.

ISBN-10 vs ISBN-13

Older books carry a 10-digit ISBN. Google asks sellers to submit the ISBN-13 and to convert ISBN-10s. The conversion follows the same pattern as UPC to EAN, with one twist: you put 978 in front of the first nine digits, then calculate a new check digit with the GTIN method, because ISBN-10 used a different check digit system. For example, the illustrative 12 digits 978123456789 give a GTIN check digit of 7, so the ISBN-13 would be 9781234567897.

Prefix	Meaning	Who issues it
978, 979	ISBN (books)	National ISBN agencies
977	ISSN (magazines, serials)	The ISSN system, not GS1 or barcode resellers
Other GS1 prefixes	Regular products (EAN/UPC)	National GS1 offices to brand owners

If you sell both books and other products, keep the two apart in your catalogue: books under ISBN, everything else under EAN or UPC. Some marketplaces have separate ISBN fields, and a book listed with a non-978/979 EAN is likely to be rejected or merged wrongly.

ASIN, FNSKU, SKU and MPN: identifiers that are not GTINs

A product page on a marketplace or in a feed is full of codes. Only some are GTINs. Mixing them up is one of the most common reasons a listing ends up attached to the wrong product, so it pays to know which is which.

Identifier	Who assigns it	Scope	Is it a GTIN?	Typical use
EAN / UPC (GTIN)	The brand owner, from a number range licensed or bought	Global	Yes	Identifying the product everywhere
ASIN	Amazon	Amazon only	No	Amazon's internal catalogue ID
FNSKU	Amazon	Amazon FBA only	No	Label that tracks your stock in Amazon's warehouses
SKU	You (the seller)	Your business	No	Stock control, order handling
MPN	The manufacturer	That manufacturer's range	No	Part or model number; paired with brand in feeds
BPID	bol.com	bol.com only	No	Groups several EANs of one product

ASIN and FNSKU

The ASIN (Amazon Standard Identification Number) is the ID Amazon gives to each product page in its catalogue. When you create a new listing with a GTIN, Amazon creates an ASIN and links it to that GTIN. Outside Amazon, an ASIN means nothing.

The FNSKU is the label Amazon uses for stock in its fulfilment centres, so it can tell your units of an ASIN apart from another seller's units. It is printed as a barcode, which is why sellers sometimes mistake it for an EAN. It is not one and should never go into a GTIN field elsewhere. The rules for creating Amazon listings, including GTIN exemptions and Brand Registry, are covered in our article on EAN codes for Amazon.

SKU

A SKU (stock keeping unit) is your own internal code: CANDLE-LAV-200 for a 200 g lavender candle, for example. You can make SKUs up freely and change them whenever you like. Google explicitly says not to put SKUs into the GTIN, brand or MPN fields (Google: unique product identifiers). It is fine, and often helpful, to have both: a SKU for your stock system and an EAN for the outside world.

MPN

The MPN (manufacturer part number) is the model or part number a manufacturer gives its product, such as the code on the back of a printer cartridge. It is unique only within that brand, which is why feeds pair it with the brand name. For own-brand or private-label goods without a GTIN, Google accepts brand plus MPN instead. eBay likewise treats brand and MPN as part of the product identifier set.

BPID on bol.com

bol.com groups several EANs of what it sees as one product, such as different pack sizes or regional versions, under one bol Product ID (BPID) (bol.com API documentation). Like the ASIN, it is a platform ID and not a GTIN. For how bol.com handles shared listings and duplicate EANs, see our guide to EAN codes for bol.com.

The number vs the barcode: symbologies explained

Much of the confusion between EAN, UPC and GTIN comes from the fact that the same words describe two things: the number and the barcode that carries it. GS1's terminology helps here. The GTIN is the number. EAN-13, UPC-A, EAN-8, ITF-14, GS1-128, GS1 DataMatrix and QR codes are symbologies: ways of drawing a number so a scanner can read it.

Barcode (symbology)	Carries	Where you see it
EAN-13	GTIN-13 (also ISBN, ISSN)	Consumer products worldwide
UPC-A	GTIN-12	Consumer products, US and Canada
EAN-8	GTIN-8	Very small packs
UPC-E	Compressed GTIN-12	Small packs, North America
ITF-14	GTIN-14 (or padded GTIN-13)	Cartons and outer cases
GS1-128	GTIN-14 plus extra data (batch, dates)	Logistics labels, pallets
GS1 DataMatrix / QR (GS1 Digital Link)	GTIN plus extra data or a web link	Healthcare, and increasingly consumer packs

GS1 calls EAN/UPC the oldest and most widely used of its barcodes, printed on virtually every consumer product in the world. The practical consequence for sellers: the barcode image is the easy part. You can generate an EAN-13 barcode for free from a number you hold. What you cannot do is make up the number itself, because it has to be unique and, on some channels, traceable to your company.

Will 2D codes replace EAN and UPC?

Not soon. GS1's "Sunrise 2027" goal is for retail point-of-sale systems worldwide to be able to scan 2D barcodes, such as GS1 DataMatrix and QR codes carrying GS1 Digital Link, by the end of 2027. It is a readiness milestone, not a mandate for brands. GS1's own support pages say that today a GS1 QR code "needs to be used alongside an EAN or UPC barcode" (GS1 support). The GTIN inside a 2D code is the same number as in your EAN, so the identifier does not change; only the way it is drawn does. Your EAN-13 barcode remains valid as of October 2026.

Which identifier does each channel ask for?

Forms rarely use consistent names. One platform has a "Barcode" field, another asks for a "Product ID" with a type dropdown, a feed wants gtin. The table below translates the common field names into the identifier you should enter. Channel rules are as of October 2026; check the platform's help pages before you list.

Channel / field	What to enter	Notes
Google Merchant Center gtin	GTIN-8, -12, -13 or -14 (UPC-E converted to 12 digits, ISBN-10 converted to ISBN-13)	Recommended where the product has a manufacturer GTIN; own-brand products can use brand + MPN
Google mpn	Manufacturer part number	Not your SKU
Amazon "Product ID" + type	UPC, EAN, ISBN, JAN or GTIN, matching the type you pick	Amazon checks codes against GS1 data; GTIN exemption possible for some products
bol.com	EAN or ISBN	GS1-registered EAN required for branded items; for unbranded items bol.com says it does not yet enforce registration
eBay product identifiers	EAN, UPC or ISBN, plus brand and MPN	"Does not apply" allowed when there is genuinely no code
Kaufland	EAN	One product page per EAN, shared by all sellers
Shopify variant "Barcode"	UPC, EAN, ISBN or GTIN	Since API version 2026-10, up to 20 typed identifiers per variant
Warehouse / wholesale	GTIN-13 for units, GTIN-14 for cartons	Ask which level they need

Google Shopping

Google treats all four GTIN lengths as one attribute. It asks for a GTIN when the product has a manufacturer-assigned one, says products without a GTIN don't need one, and wants a valid check digit and no restricted or coupon prefixes (02, 04, 2, 05, 98, 99, 981–984). Every colour or size variant needs its own GTIN. Our article on GTINs for Google Shopping and identifier_exists explains when to leave the field empty.

Shopify and other webshops

No webshop platform requires a GTIN to sell in your own shop, but the field feeds your Google listings and any marketplace integrations. Shopify's API version 2026-10 replaced the single barcode field with a barcodes connection that holds up to 20 identifiers per variant, each typed as UPC, EAN, ISBN, GTIN or ASIN and validated against its standard (Shopify changelog). That makes the difference between the types more visible than before: an ASIN can now sit next to an EAN without being mistaken for one.

Amazon and bol.com

Both catalogue marketplaces care about more than the format. Amazon has long stated that it verifies UPCs and EANs against the GS1 database and treats codes that don't match GS1's information as invalid. bol.com requires a GS1-registered EAN for branded items, while for unbranded items it says it does not yet enforce registration (bol.com partner platform, checked October 2026). So for these two channels, the identifier type is only half the question; who the number is licensed to is the other half.

Worked example: one product, several identifiers

To see how the pieces fit, follow a fictional seller, "a candle maker" selling a lavender candle in two sizes through her own shop, bol.com and Google Shopping, and supplying a small gift shop with cartons of 12.

Item	SKU (her own)	GTIN	Notes
Lavender candle 200 g	LAV-200	GTIN-13 no. 1	Printed as EAN-13 on the label
Lavender candle 400 g	LAV-400	GTIN-13 no. 2	Different size, so a new GTIN
Gift set: both candles	LAV-SET	GTIN-13 no. 3	A bundle she creates is a new trade item
Carton of 12 × 200 g for the gift shop	LAV-200-C12	GTIN-14 or a fresh GTIN-13	Only needed if the shop scans cartons

On Google Shopping she submits GTIN-13 no. 1 and no. 2 in the gtin field and her brand name in brand. Her SKUs go into her own shop system and the id field, never into gtin. On bol.com, whether her non-GS1 codes are suitable depends on how bol.com classifies the candles: as a brand, bol.com requires GS1-registered EANs; as unbranded items, bol.com currently does not enforce registration. If she plans to sell the candles through a retail chain later, that is the moment to choose GS1, because chains check that the GTIN is registered to the supplier.

She does not need a UPC at all, even if a customer in the US orders: her EAN-13s work there too. And she never needs an ISBN, unless she publishes the accompanying candle-making booklet as a book.

Where do EAN and UPC numbers come from?

The identifier type tells you the format; it does not tell you whose number it is. GS1 describes itself as the only official provider of GS1 GTINs, and you get them by joining your national GS1 office, which licenses you a company prefix or individual numbers, usually for an annual fee. GS1 UK, for example, charges £50 a year for 10 GTIN-13s for businesses with turnover up to £99,999 (renewals from 1 April 2025), and GS1 Nederland charges €61 a year for 10 codes plus a €28 annual contribution for the smallest businesses. Prices differ per country, and the right to use the numbers ends when you stop paying.

Independent suppliers also sell valid EAN-13 numbers. GTINcodes.com is one of them: it supplies valid EAN-13 numbers from its stock, issues each one only once and registers it to the buyer in its own GTINcodes register, where anyone can check a code. That is not a GS1 membership. In GS1's own lookup, Verified by GS1, a number bought this way shows the original licence holder or no data at all, not the buyer.

So EAN vs UPC is not the question that decides whether a code will be accepted. The questions are: does the channel check GS1 licence data, and is the product branded? For your own webshop, eBay, Kaufland and similar channels where the rule is "a valid, unique EAN", and for unbranded items on bol.com where registration is currently not enforced, a registered reseller code can be a practical fit. GS1 is the better choice for supermarkets and retail chains, Zalando, branded products on Amazon and bol.com, and anyone who needs their company name to appear in GS1's registry. Our honest comparison of GS1 membership and buying from a reseller sets out the costs and trade-offs per country.

If you are given a code by a supplier or a previous owner and want to know who it is registered to, look it up in Verified by GS1, and for codes supplied by GTINcodes.com, use the GTINcodes code check. The two registers answer different questions, so a result in one does not replace the other.

Common mix-ups between EAN, UPC and GTIN (and how to fix them)

Most "invalid product ID" messages are not caused by fake codes but by small formatting mistakes. These are the ones we see most often in seller questions.

1. A 13-digit EAN in a UPC field (or the reverse)

If you choose "UPC" and paste 13 digits, many systems reject the value as the wrong length. Choose "EAN" for 13 digits and "UPC" for 12. If your EAN starts with 0 and the platform only offers UPC, drop the leading zero. If you choose "EAN" and paste a 12-digit UPC, add a leading zero.

2. Lost leading zeros in spreadsheets

Spreadsheet programs treat codes as numbers and silently remove leading zeros, so 0012345678905 becomes 12345678905, which has 11 digits and fails every check. Format the column as text before pasting, or store codes with an apostrophe in front. Long codes can also turn into scientific notation such as 8.71235E+12, which destroys the number entirely.

3. Spaces, dashes and hidden characters

The digits printed under a barcode are often grouped with spaces, and ISBNs are often written with hyphens (978-1-23-456789-7). Feeds and marketplace fields expect digits only. Strip spaces, hyphens and invisible characters copied from PDFs before uploading.

4. The same code on every variant

A T-shirt in three sizes and two colours is six products and needs six GTINs. Using one EAN for all variants is a classic cause of "EAN already in use" errors and of reviews attaching to the wrong size. GS1 Netherlands gives the example of black and white socks in three sizes: six codes, and six more if you also sell 3-packs.

5. An FNSKU or SKU in the GTIN field

FNSKUs and SKUs often contain letters. Neither is a GTIN. If a feed rejects your "GTIN" because it contains letters, it is almost certainly one of these.

6. A restricted or coupon prefix

Codes starting with 02, 04 or 2 are reserved for in-store use, such as variable-weight items labelled at the deli counter, and codes starting with 05, 98 and 99 are for coupons. Google rejects them in product feeds. If a supplier's barcode starts with 2, it was probably printed by the shop for internal use and is not a GTIN you can list with.

7. Assuming the check digit proves the code is legitimate

The check digit only catches typos and misreads. A code that passes the check can still be unregistered, already in use or licensed to another company. Use the check digit to catch errors and a register lookup to answer ownership questions. GS1 explains the calculation on its check digit page.

Quick troubleshooting order

1. Count the digits: 8, 12, 13 or 14. Anything else is a formatting error.
2. Check that the type you selected matches the length (UPC = 12, EAN = 13).
3. Recalculate the check digit. A wrong one usually means a typo or a lost zero.
4. Check the prefix is not 02, 04, 2x, 05, 98 or 99, and that only books use 978/979.
5. Search the marketplace for the code to see whether it is already attached to another product.
6. Look the code up in the relevant register to confirm who it is registered to.

Summary: EAN, UPC, GTIN and ISBN at a glance

Use this checklist when you set up products or fill in a marketplace form.

• GTIN is the family name. It comes in 8, 12, 13 and 14 digits, all with the same check digit method.
• EAN-13 = GTIN-13. The standard for consumer products outside North America. "EAN" and "GTIN-13" mean the same 13 digits.
• UPC-A = GTIN-12. The North American standard. Add a leading 0 and it is a valid EAN-13; an EAN starting with 0 becomes a UPC by dropping the 0.
• EAN-8 = GTIN-8, only for genuinely small packs. Usually a smaller EAN-13 barcode is the better solution.
• GTIN-14 / ITF-14 is for cartons and outer cases, not for the single item a customer buys.
• ISBN (978/979) is for books and comes from your national ISBN agency; ISSN (977) is for magazines. One ISBN per edition and format.
• ASIN, FNSKU, SKU, MPN and BPID are not GTINs. Keep them out of GTIN fields.
• The prefix shows the issuing GS1 office, not the country of origin.
• A valid check digit proves format, not ownership. Check registration separately.
• Give every variant and every bundle its own GTIN, and never invent numbers.
• For retail chains, Zalando and branded products on Amazon or bol.com, choose GS1. For your own shop and channels that ask for a valid, unique EAN, a code registered to you by a supplier such as GTINcodes.com can work; see the current code packages in our shops.