FB2 (FictionBook 2)

FictionBook 2 (FB2) stores a whole book in one XML file: metadata, the text marked up by structure (sections, titles, paragraphs, poems, epigraphs, notes) and the images as Base64 data. It describes what the text is, not how it looks: there is no layout or CSS, so every reader applies its own formatting. FB2 is the dominant e-book format in Russian-speaking countries and is widely supported by e-reader apps and devices (PocketBook, ONYX BOOX, KOReader, FBReader).

Because it’s plain XML with a fixed schema, FB2 is easy to generate, validate and convert. Large online libraries distribute books as .fb2.zip: a ZIP archive containing one .fb2 file, which cuts the size by 3 to 4 times.

When to use FB2#

• Use for text-centered books (fiction, non-fiction without complex layout) when your readers use FB2-capable apps or devices.
• Use when you need a simple, single-file, schema-validated format for archiving or converting book text.
• Avoid for books that need precise layout, tables with styling, fonts or interactivity: use EPUB.
• Avoid when the audience reads on Kindle or Apple Books, which don’t open FB2: convert to EPUB or AZW3.

File structure#

<?xml version="1.0" encoding="UTF-8"?>
<FictionBook xmlns="http://www.gribuser.ru/xml/fictionbook/2.0"
             xmlns:l="http://www.w3.org/1999/xlink">
  <description>
    <title-info>
      <genre>sf</genre>
      <author><first-name>Jane</first-name><last-name>Doe</last-name></author>
      <book-title>My Book</book-title>
      <annotation><p>A short description.</p></annotation>
      <date value="2026-01-15">2026</date>
      <coverpage><image l:href="#cover.jpg"/></coverpage>
      <lang>en</lang>
      <sequence name="My Series" number="1"/>
    </title-info>
    <document-info>
      <author><nickname>converter</nickname></author>
      <program-used>My Tool 1.0</program-used>
      <date value="2026-01-15">2026-01-15</date>
      <id>6f1c2a3b-4d5e-4f60-8a7b-9c0d1e2f3a4b</id>
      <version>1.0</version>
    </document-info>
    <publish-info>
      <publisher>My Press</publisher>
      <year>2026</year>
      <isbn>978-0-00-000000-0</isbn>
    </publish-info>
  </description>
  <body>
    <title><p>My Book</p></title>
    <section>
      <title><p>Chapter 1</p></title>
      <epigraph><p>An epigraph.</p><text-author>Someone</text-author></epigraph>
      <p>First paragraph with <emphasis>italic</emphasis> and <strong>bold</strong> text.<a l:href="#n1" type="note">[1]</a></p>
      <empty-line/>
      <image l:href="#pic1.png"/>
    </section>
  </body>
  <body name="notes">
    <section id="n1"><title><p>1</p></title><p>The footnote text.</p></section>
  </body>
  <binary id="cover.jpg" content-type="image/jpeg">/9j/4AAQSkZJRgABAQ...</binary>
  <binary id="pic1.png" content-type="image/png">iVBORw0KGgoAAAANSUhEUg...</binary>
</FictionBook>

Top-level elements#

description#

An author has first-name, middle-name, last-name, nickname, home-page, email and id.

body content#

Inline markup: strong, emphasis, strikethrough, sub, sup, code, style (named style), and a l:href="..." for links; type="note" marks a footnote link to a section in the notes body.

Encoding and validation#

The XML declaration gives the encoding: modern files use UTF-8, but many older Russian files are in windows-1251, so a parser must honor the declaration instead of assuming UTF-8. The official schema (FictionBook.xsd with FictionBookGenres.xsd, FictionBookLinks.xsd, FictionBookLang.xsd) validates a file, but many files found online are not fully valid; robust readers parse leniently.

FB2.ZIP and FBZ#

.fb2.zip and .fbz are ordinary ZIP archives (usually DEFLATE) that contain a single .fb2 file. Readers that support FB2 generally open them directly. To process one, unzip it and read the .fb2 inside.

Converting#

• FB2 to EPUB or AZW3: ebook-convert book.fb2 book.epub with Calibre, or fb2cng, a dedicated converter to EPUB 2/3, KEPUB and Kindle formats.
• EPUB to FB2: ebook-convert book.epub book.fb2 (Calibre has an FB2 output plugin).
• FB2 to PDF: mutool convert -o book.pdf book.fb2 (MuPDF).
• Edit: FictionBook Editor (Windows) edits FB2 files visually and validates them against the schema.

Specifications and documentation#

• FictionBook 2.1 schema on GitHub: the official XSD files (FictionBook.xsd, genres, links, languages)
• FB2 on the MobileRead wiki: overview of the format and supporting software
• FictionBook on Wikipedia
• FictionBook 3 on GitHub: the successor format (a ZIP package with XML), rarely used

Software that opens FB2 files#

Libraries#

Open-source libraries that read and write FB2. See all FB2 libraries for a comparison.

Related formats#

• EPUB: the international e-book standard; richer layout, CSS and fonts
• MOBI / AZW3: Kindle formats; FB2 converts to AZW3 for Kindle devices
• ZIP: the container of .fb2.zip and .fbz
• TXT: plain text, the usual source for simple FB2 conversions