What is a .fb2 file?
FictionBook eBook · eBook · FictionBook community · 2004
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.
What opens 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.
Windows
- Calibre
- FBReader
- Cool Reader
macOS
- Calibre
- FBReader
Linux
- Calibre
- FBReader
- Cool Reader
Open a .fb2 file step by step
- Confirm the file really is a .fb2. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Calibre or FBReader.
- On Mac, use Calibre or FBReader.
- On Linux, try Calibre or FBReader.
- Still stuck? Convert the .fb2 to epub, which opens more widely.
Why can't I open my .fb2 file?
Almost always because no installed app understands FB2. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .fb2 at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
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.
What is the .fb2 file signature (magic bytes)?
A .fb2 file starts with the hex bytes 3C 3F 78 6D 6C, which read as <?xml in ASCII. Programs identify FB2 by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for FB2. For a full breakdown, see the XML file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 3C 3F 78 6D 6C | 0 | <?xml | '<?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
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