What is a .fb2 file? (FB2)

An .fb2 file is a FictionBook eBook, an open XML format popular in Russia and Eastern Europe. It describes a book's structure and metadata in a single XML file, with any images embedded as base64.

What is a .fb2 file used for?

Because FB2 is one self-contained XML file, it is simple and easy to convert. It stores semantic structure (chapters, epigraphs, notes) rather than fixed layout, so it reflows to any screen.

Most e-reader software and Calibre open FB2, and it converts cleanly to EPUB or MOBI.

How to open a .fb2 file

The .fb2 format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .fb2 file.

Windows

Calibre
FBReader
Cool Reader

macOS

Calibre
FBReader

Linux

Calibre
FBReader
Cool Reader

How to convert a .fb2 file

You can convert a .fb2 file to epub, mobi, pdf using a conversion tool or the export menu of an app that opens it.

.fb2 file signature (magic bytes)

Programs recognise a .fb2 file by the bytes at the start of the file, not by its name. These are the signatures for FB2.

Hex signature	Offset	Note
3C 3F 78 6D 6C	0	'<?xml' (FB2 is XML)

See the full magic-numbers reference for every format.

Frequently asked questions

What is a .fb2 file?

An .fb2 file is a FictionBook eBook, an open XML format popular in Russia and Eastern Europe. It describes a book's structure and metadata in a single XML file, with any images embedded as base64.

How do I open an .fb2 file?

Use Calibre or FBReader, both free and both supporting FictionBook. Many mobile e-reader apps read it too.

What is FB2 used for?

It is an open eBook format, widely used in Russian-language libraries, that keeps a book's structure in a single XML file.

How do I convert FB2 to EPUB?

Import the .fb2 into Calibre and convert to EPUB, which more devices support.

Related formats

Sources

Details on this page were checked against authoritative references:

Wikipedia: FictionBook