What Is an ISBN? Book Numbers, ISBN-10 and ISBN-13
An ISBN (International Standard Book Number) is the 13-digit number that identifies one book in one format and edition from one publisher. It starts with 978 or 979 and is printed above the EAN-13 barcode on the back cover. This guide explains how to read its five parts, ISBN-10 vs ISBN-13 and how to get an ISBN.
By the Barcode.codes editorial teamReviewed
What an ISBN Identifies
An ISBN identifies one book publication: one title, in one format and one edition, from one publisher, so booksellers, libraries and distributors can order the right one.
One ISBN for Each Format and Edition
The hardcover, the paperback and the ebook of the same title each need their own ISBN, as the ISBN Users' Manual sets out. That is how a bookseller can tell the formats apart when it orders, stocks and sells them.
Books Only
GS1's standard calls the ISBN the identifier for hardcover books and paperbacks, and says ISBNs shall not be given to products that are not books. A mug or a T-shirt sold with a book gets a GTIN and a barcode like any other retail product.
How to Read an ISBN Number
Read an ISBN-13 from left to right in five parts: the prefix 978 or 979, the registration group, the registrant (the publisher), the publication and the check digit.
| Part | In the example | What it tells you |
|---|---|---|
| Prefix | 978 | A book number: GS1 gave 978 and 979 to the ISBN system |
| Registration group | 0 | The ISBN agency's language area or country, not where the book was printed |
| Registrant | 306 | The publisher or imprint the number was issued to |
| Publication | 40615 | The title, in one format and edition |
| Check digit | 7 | Calculated from the other 12 digits to catch typing errors |
Why the Parts Have Different Lengths
The International ISBN Agency publishes ranges that set how long the group and the registrant are; a short registrant element leaves more digits for titles, so it suits a publisher with many books. That is why the hyphens sit in different places from one ISBN to the next.
Try it: barcode number check
A UPC, EAN, GTIN-14 or ISBN number, with its check digit.
- Type
- EAN-13 (GTIN-13)
- GS1 Prefix
- 978: Allocated to the International ISBN Agency: the number of a book (part of 979 is for printed music).
- Check digit
- 7, correct
ISBN barcode generator places the hyphens from the official ranges and draws the barcode.
ISBN-10 vs ISBN-13
An ISBN-13 has 13 digits and starts with 978 or 979; an ISBN-10 is the older 10-character form of a 978 ISBN, with a different check digit that can be X.
| Property | ISBN-10 | ISBN-13 |
|---|---|---|
| Length | 10 characters | 13 digits |
| Starts with | The registration group | 978 or 979 |
| Check digit | Mod 11: 0 to 9 or X | Mod 10: 0 to 9 |
| Example | 0306406152 | 9780306406157 |
| Barcode | The EAN-13 of its ISBN-13 | EAN-13 |
Converting Between ISBN-10 and ISBN-13
- Drop the check character of the ISBN-10: 0-306-40615-2 becomes 030640615.
- Put 978 in front: 978030640615.
- Calculate the GS1 check digit: the weighted sum is 93, so the check digit is 7 and the ISBN-13 is 9780306406157.
Going back works only for ISBNs that start with 978. Drop the 978 and the old check digit, then weight the nine digits by 10 down to 2: the sum is 130, the remainder after dividing by 11 is 9, and 11 − 9 gives the check digit 2. A remainder of 1 gives the check character X.
Try it: check digit calculator
12 digits without the check digit.
Check digit
7
9780306406157
Show the calculation
| # | Character | Value | Weight | Product |
|---|---|---|---|---|
| 1 | 9 | 9 | ×1 | 9 |
| 2 | 7 | 7 | ×3 | 21 |
| 3 | 8 | 8 | ×1 | 8 |
| 4 | 0 | 0 | ×3 | 0 |
| 5 | 3 | 3 | ×1 | 3 |
| 6 | 0 | 0 | ×3 | 0 |
| 7 | 6 | 6 | ×1 | 6 |
| 8 | 4 | 4 | ×3 | 12 |
| 9 | 0 | 0 | ×1 | 0 |
| 10 | 6 | 6 | ×3 | 18 |
| 11 | 1 | 1 | ×1 | 1 |
| 12 | 5 | 5 | ×3 | 15 |
| Sum | 93 | |||
Nearest multiple of ten at or above 93 is 100: 100 − 93 = 7
ISBNs That Start With 979
ISBNs from the 979 prefix were never issued as ISBN-10, so they have no 10-character form. GS1 gave part of 979, the range 979-0, to the ISMN for printed music.
The ISBN Barcode on a Book
On a printed book the ISBN-13 is drawn as an EAN-13 barcode, with the ISBN printed above the bars, so checkouts that scan product barcodes read books too.
The ISBN Users' Manual asks for the ISBN in human-readable form above the barcode, preceded by "ISBN" and with its hyphens. Books sold in the United States and Canada often add a 5-digit price add-on to the right of the EAN-13.
ISBN barcode generator makes the EAN-13 for your ISBN, with the price add-on if you need one.
How to Get an ISBN
ISBNs come from the ISBN agency of the publisher's country or language area, not from GS1 or from a barcode website.
- Find your agency in the International ISBN Agency's directory.
- Get one ISBN for each format and edition you publish.
- Make the EAN-13 barcode from each ISBN and place it on the back cover.
GS1 allocated the prefixes 978 and 979 to the ISBN system, and the ISBN agencies issue numbers from them. Barcode.codes draws barcodes for ISBNs you already have; it does not issue ISBNs.
Buy an ISBN Bowker's prices, a calculator for how many ISBNs you need, and free KDP ISBNs.
Frequently Asked Questions
Is an ISBN the Same as a Barcode?
No. The ISBN is the number; the barcode is the EAN-13 symbol that carries the 13 digits of the ISBN so a scanner can read them.
Does Every Book Need an ISBN?
Not under GS1's rules: a book sold in stores may also carry a GTIN like any other product, though GS1 recommends the ISBN for books. Booksellers and distributors set their own requirements, so check theirs.
What Does the X in an ISBN-10 Mean?
It is the check character for the value 10. The ISBN-10 check uses modulus 11, so the result can be 10, which is written as X; an ISBN-13 never has an X.
Does the ISBN Show Where a Book Was Printed?
No. The registration group names the agency's language area or country, such as 0 and 1 for English, not the place of printing or the publisher's address.
Sources
The facts in this guide come from these sources; the ISBN ranges are the message of October 3, 2026.
GS1 General Specifications, Release 26.0, ratified January 2026 defines the GS1 identification keys, barcodes and Application Identifiers; the text names the sections used.
ISBN Users' Manual, seventh edition, International ISBN Agency, 2017 sets one ISBN per format and edition, the ISBN printed above the barcode and the 5-digit add-on (sections 13.1 to 13.3).
ISBN range message, International ISBN Agency, message of October 3, 2026 gives the registration groups, their agencies and the registrant ranges that place the hyphens.
Find an ISBN agency, International ISBN Agency lists the national and language-area agencies that issue ISBNs.
Related Barcode Guides
- What is a UPC code?
The 12 digits, the check digit and how to get one.
- What is a GTIN?
The product number inside every retail barcode.
- How to read a barcode
What the digits mean and how to read the bars by eye.
- Barcode country codes
The GS1 prefixes and the offices that issue them.
- What is a barcode?
What a barcode is, what it holds and where it is used.