FB2 file format: what it is and how to use it

FictionBook is the XML e-book format that dominates Russian-language libraries: pure book structure, zero page layout, converted to EPUB for the rest of the world. Learn when to use it and what to choose instead.

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What is a FB2 file?

A .fb2 file is an e-book in FictionBook, an XML format born in the Russian e-book community of the 1990s that describes only structure: title, author, chapters, epigraphs, footnotes and embedded images as base64. There are no layout instructions at all, so the reader renders the text however the user prefers. It remains the standard in Russian-language libraries and archives.

When should you use FB2?

  • Russian-language collections: the format many library sites and readers assume.
  • Structure-first books: clean semantic markup that converts losslessly onward.
  • Calibre pipelines: it is a first-class citizen in open e-book tooling.

When is another format a better fit?

For distribution outside that world, EPUB is the global standard. For Kindle ecosystems the path runs through MOBI/KFX; for print replicas PDF. FB2 is best seen as a superb source format. Feed it to converters when the destination expects EPUB.

The short version: FB2 is the purist's e-book: perfect structure for its home market, and a conversion input everywhere else.

How to open a FB2 file

On Windows

Double-click the file, or open it with Calibre.

On macOS

FBReader opens FB2 files on macOS.

In your browser

Open FB2 files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • Calibre
  • FBReader
  • Cool Reader
  • PocketBook

View or convert FB2 files

A quick preview or a new format. No install, no upload.

View FB2 files Preview and inspect FB2 files Convert to FB2 Turn files into FB2 FB2 to EPUB EPUB e-book FB2 to MOBI Mobipocket e-book FB2 to XML eXtensible Markup Language

FB2 technical details

Full name
FictionBook 2
Extensions
.fb2
MIME type
application/x-fictionbook+xml, text/xml
Magic bytes
3C 3F 78 6D 6C (XML, <FictionBook>)
Compression
None (uncompressed)
Developer
FictionBook community (Dmitry Gribov)

FB2 questions, answered

How do I open a .fb2 file?

FBReader, Calibre, PocketBook and most e-readers handle it; browser extensions work too. dexrr displays and converts fb2 files directly in your browser.

Can I convert FB2 files online?

Yes, dexrr converts fb2 locally in your browser: FB2 to EPUB for modern readers or FB2 to PDF for printing.

Is FB2 better than EPUB?

Structurally it is arguably cleaner, being pure semantics without presentation. In reach, no: EPUB is the global standard every store and device speaks.

Why won't my e-reader open .fb2?

Support is concentrated in Russian-market devices and open readers. Convert to EPUB, which is the same content in the format your device expects.

Is the FB2 format outdated?

Regionally no, it is still the live standard of Russian e-book libraries; globally it lives on mostly as conversion input.