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EPUB Metadata Explained: Title, Creator, Language, ISBN, Series, and BISAC Subjects

Learn how to set accurate EPUB metadata for title, creator, language, ISBN, series, and BISAC subjects. Step-by-step checks and worked examples for indie authors.

12 min read · EpubBit Editorial Team

EPUB metadata is the set of descriptive fields inside your ebook that tells retailers, libraries, and reading apps what your book is. Get it wrong, and your book may be hard to find, misclassified, or rejected by distributors. This guide walks through the essential metadata fields—title, creator, language, ISBN, series, and BISAC subjects—with practical checks and worked examples. By the end, you will know how to verify each field and avoid common pitfalls.

Why Metadata Matters More Than You Think

Metadata drives discovery. When a reader searches for your book by title, author, or subject, the retailer's search engine relies on your metadata. If your title is misspelled or your author name is inconsistent across books, you lose sales. Metadata also controls how your book appears on a virtual shelf: series information groups books together, language determines which stores can sell it, and BISAC subjects place it in the right category. Finally, metadata is how libraries and aggregators like IngramSpark, Draft2Digital, and Kobo Plus identify your book. A single error can cause your book to be listed under the wrong genre, excluded from a store, or flagged for review.

Title and Subtitle: Getting the Main Field Right

The title field is the primary name of your book. In EPUB 3, this is expressed as dc:title in the package document (the content.opf file). You can also include a subtitle using a separate dc:title element with the title-type property set to subtitle. For example:

<dc:title id="t1">The Indie Author's Guide to EPUB</dc:title>
<meta refines="#t1" property="title-type">main</meta>
<dc:title id="t2">Metadata, Validation, and Distribution</dc:title>
<meta refines="#t2" property="title-type">subtitle</meta>

If you are using a tool like EpubBit, it will handle the XML for you, but you still need to enter the correct text. Common mistakes include using all caps (which looks like shouting in some stores), adding unnecessary punctuation, or including series information in the title field. Keep the main title clean. If your book is part of a series, put the series name in the series field, not in the title. For example, use Title: A Novel only if that is the official title; otherwise, keep it as Title and let the series metadata do the work.

Step-by-step title check

  1. Open your EPUB's package document (or your EpubBit project metadata panel).
  2. Verify that the main title matches the title on your cover exactly, including capitalization and punctuation.
  3. Check that any subtitle is in a separate field and marked as subtitle.
  4. Ensure the title does not contain series information or author names.
  5. If your book has a subtitle, confirm that retailers display it correctly by previewing your book in a reading app.

Creator: Author, Editor, and Contributor Roles

The creator field (dc:creator) is where you list the author. In EPUB 3, you can specify the role using the role property with a MARC relator code. The most common is aut for author. For example:

<dc:creator id="creator">Jane Doe</dc:creator>
<meta refines="#creator" property="role" scheme="marc:relators">aut</meta>

If you have multiple authors, list them in the order they should appear. Use the file-as property to specify the sort order, typically "Doe, Jane". This helps retailers and libraries sort your book correctly. For example:

<meta refines="#creator" property="file-as">Doe, Jane</meta>

Do not put multiple authors in a single dc:creator element separated by commas; use separate elements for each. Also, be consistent: if you use "Jane Doe" on one book, use the same spelling on all books. Inconsistencies can split your author page on retailers.

Step-by-step creator check

  1. List each author in a separate dc:creator element.
  2. Add the role property with aut for authors, edt for editors, ill for illustrators, etc.
  3. Add the file-as property for each creator to control sorting.
  4. Verify that the author name matches your other books exactly.
  5. If you use a pen name, ensure it is consistent across all metadata and your cover.

Language: The Often-Overlooked Field

The language field (dc:language) tells retailers and reading systems what language your book is in. Use a valid BCP 47 language tag, such as en for English, en-US for American English, en-GB for British English, fr for French, etc. If your book contains multiple languages, you can list multiple dc:language elements, but the first one should be the primary language. For example:

<dc:language>en-US</dc:language>

Why does this matter? Some retailers use language to filter search results and recommendations. If you set the wrong language, your book may not appear in the right storefront. For example, if you publish a Spanish-language book but set the language to English, it may be listed in the English store and confuse readers. Also, accessibility features like text-to-speech may rely on language tags for correct pronunciation.

Step-by-step language check

  1. Determine the primary language of your book's text.
  2. Use the appropriate BCP 47 tag. For a full list, see the IANA Language Subtag Registry (verify current documentation).
  3. If your book has significant content in another language, add a second dc:language element.
  4. Check that your EPUB editing tool or EpubBit has set the language correctly; some tools default to en.

ISBN: When You Need One and How to Use It

An ISBN (International Standard Book Number) is a 13-digit identifier for your book. It is not required for all EPUBs, but many retailers and libraries require it for distribution. If you sell directly to readers from your own website, you may not need an ISBN. However, if you want your book in libraries, bookstores, or aggregated catalogs, you likely need one. In EPUB metadata, the ISBN is expressed as a dc:identifier with the scheme ISBN. For example:

<dc:identifier id="pub-id">978-1-234567-89-0</dc:identifier>
<meta refines="#pub-id" property="identifier-type" scheme="onix:codelist5">15</meta>

The code 15 in ONIX codelist 5 means ISBN-13. If you use an ISBN-10, the code is 02. Always use the hyphenated form for readability, but the hyphens are not part of the number; they are for display. The check digit is the last digit and is calculated using a specific algorithm. For ISBN-13, multiply each of the first 12 digits by alternating weights of 1 and 3, sum the results, and find the remainder when divided by 10. The check digit is (10 - remainder) mod 10. For example, for the first 12 digits 978123456789, the sum is 9*1 + 7*3 + 8*1 + 1*3 + 2*1 + 3*3 + 4*1 + 5*3 + 6*1 + 7*3 + 8*1 + 9*3 = 9+21+8+3+2+9+4+15+6+21+8+27 = 133. 133 mod 10 = 3. Check digit = (10-3) mod 10 = 7. So the full ISBN-13 is 978-1-234567-89-7. You can verify your ISBN with an online calculator or by using EpubBit's validation tools.

Step-by-step ISBN check

  1. Decide if you need an ISBN. Check the current requirements of your chosen retailers and distributors.
  2. Purchase an ISBN from your national ISBN agency (e.g., Bowker in the US, Nielsen in the UK).
  3. Enter the ISBN in your EPUB metadata as a dc:identifier with the correct scheme.
  4. Verify the check digit using the algorithm above or a trusted calculator.
  5. Ensure the ISBN matches the one on your copyright page and anywhere else it appears.

Series Metadata: Grouping Your Books

If your book is part of a series, you should include series metadata. In EPUB 3, this is done with meta properties: belongs-to-collection for the series name, collection-type set to series, and group-position for the book's number in the series. For example:

<meta property="belongs-to-collection" id="series">The Indie Author's Toolkit</meta>
<meta refines="#series" property="collection-type">series</meta>
<meta refines="#series" property="group-position">1</meta>

Some retailers also use a separate dc:identifier for the series, but this is less common. The key is to be consistent: use the same series name and numbering across all books. If you have a series with a prequel or a novella, decide on the reading order and stick to it. For example, if your series has three books, number them 1, 2, 3. If you later add a prequel, you might number it 0 or 0.5, but check how retailers display such numbers. Some retailers sort by group-position, so using decimals can work, but it is safer to use whole numbers and adjust the series order in your retailer dashboard if needed.

Step-by-step series check

  1. Decide on a series name that is unique and not confusing with other series.
  2. For each book, add the belongs-to-collection meta with the series name.
  3. Add collection-type set to series.
  4. Add group-position with the book's number.
  5. Verify that the series name and number match what you entered in your retailer's dashboard.

BISAC Subjects: Getting Found in the Right Category

BISAC (Book Industry Standards and Communications) subject codes are used by retailers and libraries to categorize books. They are alphanumeric codes like FIC000000 for Fiction / General, FIC027000 for Fiction / Romance / General, etc. In EPUB metadata, BISAC codes are typically included as dc:subject elements with the scheme BISAC. For example:

<dc:subject id="subject1">FIC027000</dc:subject>
<meta refines="#subject1" property="authority">BISAC</meta>

You can include multiple BISAC codes, but most retailers recommend using at least one and no more than three. The first one should be the most specific and accurate. For example, if your book is a cozy mystery, use FIC022000 (Fiction / Mystery & Detective / General) or a more specific code like FIC022070 (Fiction / Mystery & Detective / Cozy). Avoid using overly broad codes like FIC000000 unless your book truly fits. To find the right code, consult the current BISAC Subject Headings list from BISG (Book Industry Study Group). Verify the latest version, as codes are updated periodically.

In addition to BISAC, you can include keywords in your retailer's dashboard, but those are not part of the EPUB metadata. However, some reading systems use dc:subject for search, so including relevant keywords as subjects can help. For example, you might add dc:subject with the value "cozy mystery" without a scheme. But be careful: too many subjects can dilute the signal. Stick to BISAC codes for categorization and use retailer keywords for search optimization.

Step-by-step BISAC check

  1. Identify the primary BISAC code for your book using the current BISG list.
  2. Add it as a dc:subject with the authority meta set to BISAC.
  3. Add up to two secondary codes if they are accurate and helpful.
  4. Ensure the codes match the categories you selected in your retailer's dashboard.
  5. Review your book's placement in a retailer's store to see if it appears in the expected category.

Putting It All Together: A Metadata Checklist

Before you publish, run through this checklist. You can do it manually by inspecting the content.opf file, or use EpubBit's metadata editor and validator to catch errors. EpubBit can help you ensure that all required fields are present and correctly formatted, and it can flag common issues like missing language tags or invalid ISBNs.

  1. Title: Main title matches cover; subtitle is separate and marked.
  2. Creator: Each author in a separate field with role and file-as.
  3. Language: Valid BCP 47 tag; primary language first.
  4. ISBN: Correct 13-digit number with valid check digit; scheme set to ISBN.
  5. Series: Series name, type, and position set consistently across books.
  6. BISAC: At least one accurate code; no more than three; matches retailer categories.
  7. Other: Publisher, date, and rights fields are also important; ensure they are filled.

After editing, always validate your EPUB with EPUBCheck or a similar tool. Metadata errors are among the most common validation failures, but they are easy to fix once you know what to look for.

Conclusion

Metadata is not glamorous, but it is the backbone of your book's discoverability and sales. By carefully setting title, creator, language, ISBN, series, and BISAC subjects, you give your book the best chance of being found by the right readers. Take the time to verify each field, use consistent naming across your books, and validate your EPUB before distribution. With these practices, you will avoid the common pitfalls that trip up indie authors and small publishers. Remember to check the current official documentation from retailers and standards bodies, as requirements can change. Your future self—and your readers—will thank you.