ISBN - Indispensable for the sale of your book in bookstores

If you browse through your favorite bookstore, you'll notice that all the books there have an ISBN. But what can you read from this number and what is it good for?

What is the ISBN?

The International Standard Book Number, or ISBN for short, is a unique identification number for books. The numerical code, which now consists of 13 digits, contains all the necessary information about the book, such as from which language area it originates and under which publisher it was published. Each number is assigned only once worldwide. Even if the book is out of print, the ISBN will always be assigned to it. In Germany, ISBNs are issued to publishers and private individuals by MVB Marketing- und Verlagsservice des Buchhandels GmbH.

What does an ISBN consist of?

The numerical sequence of the ISBN consists of five parts and is now 13 digits long. In addition to the prefix and the check digit at the end, the number also contains the group number, the publisher number and the title number of the book.


The prefix, i.e. the preceding number 978 or 979, has a fixed value of three digits.


Group number

The subsequent group number, on the other hand, depends on the respective language area. If a book is produced in a German-speaking country, the country code with the number 3 is one-digit. However, it can have up to five digits; Luxembourg, for example, has the country code 99959. However, the country number does not have to mean at the same time that the book was also written in the corresponding language, but indicates where it was published.


Publisher number

The publisher code can also vary in length. The larger a publisher is, the smaller the publisher code. This leaves more space for the subsequent article codes. For example, S. Fischer Verlag with the number 10 has a two-digit publisher's code and can publish more titles accordingly. This leaves six digits before the check digit - in this case up to 999,999 titles. Smaller publishers, on the other hand, publish fewer books and therefore do not need as many digits in the title number. The publisher code can then have up to seven digits, leaving only one digit for the article numbers, and only nine books can be published under this number. Titles published via tredition are given the publishing house number 347.


Title number

As the penultimate part of the ISBN, there is a sequential title number for each of the publisher's books. Depending on how many titles the publisher expects to produce, it is given a longer or shorter publisher number to leave space for the article number accordingly. At tredition, for example, the three-digit publisher number means that a total of 99,999 titles can be published.


Check digit

The check digit at the end of an ISBN ensures that the number is correct. It can be calculated using a certain formula. Online tools can be helpful for this, such as an Check digit calculator. However, it is no longer necessary to check the ISBN if you get it from a publisher or the ISBN agency in Frankfurt am Main.

In this example, the check digit is calculated as follows: The first twelve digits of the ISBN are alternately multiplied by 1 and 3 and added together.

9x1 + 7x3 + 8x1 + 3x3 + 3x1 + 4x3 + 7x1 + 9x3 + 9x1 + 9x3 + 9x1+ 9x3

= 9 + 21 + 8 + 9 + 3 + 12 + 7 + 27 + 9 + 27 + 9 + 27

= 168

The difference of this sum to the next multiple of 10 is the check digit, so in this example 168 + 2 = 170. If the sum is divisible by 10, the check digit is 0.


Where can I get an ISBN?

In Germany the ISBN are published by the agency MVB Marketing- und Verlagsservice des Buchhandels GmbH in Frankfurt am Main. In Austria, you can obtain the number from the Main Association of the Austrian Book Trade in Vienna and in the German-speaking part of Switzerland, this task lies with the Swiss Booksellers and Publishers Association in Zurich. Whether you are a publisher or self-publisher - here you have the option of buying individual ISBNs or applying for a publisher number.

As a published author, you don't have to worry about that. Published you in the Self-PublishingCheck with your service provider to see if your book will be assigned an ISBN. Don't forget to add your book to the Directory of books in print (VLB) to be registered. This also take over Publishing houses and self-publishing providers for you.

Where is the ISBN in the book?

At best, the ISBN should be on the inside and outside of the book. Usually it is on the back cover at the barcode as well as inside, before the actual content begins, in the Title bar. However, there are no clear rules here. Even if the number is not visible on the outside, for example, the ISBN is valid and the work can be ordered via the book trade. For specific questions, it is better to contact the issuing office directly.

How many ISBN do I need for my book?

You wrote a story, so you just need an ISBN, right? Not exactly. Because each book needs its own ISBN, even if the content is the same. For example, if you publish a paperback, a hardcover and an e-book, you need three ISBNs. But the list of variants goes far beyond that. Special editions, modified reissues, re-releases by a different publisher or as a book for a film are just a few examples of what you need a separate ISBN for.

Even if all books tell the same story, they need their own ISBN - unless it's a completely unchanged new edition. But a new cover or text changes are reason for a new ISBN.

Why do I need an ISBN?

With the book title you are looking for, are there different books by different authors or how was the author's name spelled again? An ISBN helps tremendously when your reader is looking for your book. While it is not mandatory to put an ISBN on your book, this makes it easily available through bookstores. If you publish for private use or sell the book exclusively yourself, it is not absolutely necessary to apply for an ISBN. However, the number is necessary if you want to list your book in the directory of available books. You can only sell your book with an ISBN.

What is ISBN-10 and ISBN-13?

The ISBN-10 was first introduced in the 1970s. This had ten digits and although a combination of ten digits theoretically allows countless numbers, at some point in the English-speaking world all the numbers were used up. This is because an ISBN does not calculate from 0000000001 to 99999999, but consists of several components. Because there were no more numbers to be assigned for publishers from the English-speaking world, the ISBN-13 was introduced. Three additional digits were added as a new standard and the number was adapted to the system for international article numbers (EAN) in order to integrate books into merchandise management systems. Because the prefix was added, i.e. 978 or 979, twice as many numbers can now be assigned.


An ISBN is a unique identifier for your book. Without the number and an entry in the directory of available books, you lack a basis for listing your title in the databases of the Book Trade visible. Many questions about the ISBN can be answered via the FAQ If you have more specific questions, it is advisable to contact the awarding office directly.


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