Do I need to install anything to use this tool?

This tool generates the command for you — no installation needed here. To run the actual conversion you need Calibre (free, open-source) installed on your computer. Download it from calibre-ebook.com. The ebook-convert program ships with every Calibre installation.

What is FB2 and why use it instead of EPUB?

FB2 (FictionBook 2) is an XML-based ebook format popular in Russia and Eastern Europe. It stores the entire book in a single well-structured XML file with clean chapter tagging and author metadata. Many Russian e-readers and apps (FBReader, PocketBook, Onyx BOOX) treat FB2 as their native format, offering better typography and navigation than converted EPUB files on those devices.

Will my AZW3 file be uploaded anywhere?

No. The file inspector reads only the name and size from your local file system using the browser File API — no data leaves your device. The command generator also runs entirely in your browser. Your ebook content is never transmitted to any server.

Can I convert DRM-protected AZW3 files?

No. Calibre cannot convert AZW3 files that have Amazon DRM applied. Only DRM-free AZW3 files can be converted — this includes personal documents sent to your Kindle, ebooks purchased from DRM-free stores, and self-published works you own the source files for. Stripping DRM is illegal in most jurisdictions.

Why might the FB2 output look different from the Kindle original?

AZW3 uses proprietary Kindle-specific CSS and layout extensions. Calibre converts these to the FB2 XML model, but some differences in fonts, tables, and complex layouts are expected. FB2 is primarily a structural format — it excels at fiction with chapters but is less suited to heavily formatted technical or illustrated books.

Can I batch-convert multiple AZW3 files at once?

Yes. The tool shows bash and PowerShell batch loops after generating a command. On Linux/macOS: for f in *.azw3; do ebook-convert "$f" "${f%.azw3}.fb2"; done. Each file is processed sequentially by Calibre.

What language code should I use?

Use a two-letter ISO 639-1 code such as "en" for English, "ru" for Russian, "de" for German, or "fr" for French. The language code is stored in the FB2 metadata and helps reading apps apply correct hyphenation and text direction rules.

AZW3 to FB2 Converter

Generate a ready-to-run Calibre ebook-convert command to convert AZW3 Kindle ebooks to FB2 (FictionBook 2) format — no upload needed.

Conversion Settings

Drop your AZW3 file here

or click to select — file is not uploaded

Files

Input AZW3 file *

Filename or full path, e.g. /home/user/books/my-book.azw3

Output FB2 file

Leave blank to auto-derive from input filename.

Metadata overrides (optional)

Book title

Author

Publisher

Language

Fill in settings and click Generate Command

Your ready-to-run Calibre command will appear here.

How to Install Calibre

Windows

Download the installer from calibre-ebook.com, run it, then open a Command Prompt and type ebook-convert --version to verify.

macOS

Download the .dmg from calibre-ebook.com or run brew install --cask calibre if you use Homebrew.

Linux

Run sudo apt install calibre on Debian/Ubuntu, sudo dnf install calibre on Fedora, or use the official binary installer script from calibre-ebook.com.

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Summary

AZW3 to FB2 Converter generates precise Calibre ebook-convert commands that convert any DRM-free AZW3 Kindle ebook into FB2 (FictionBook 2) format. FB2 is widely used on Russian e-readers such as PocketBook and Onyx BOOX, and is native to apps like FBReader. Fill in your filename and optional metadata overrides, copy the generated command, and run it in any terminal with Calibre installed. The file inspector lets you confirm file details locally — nothing is ever uploaded.

How it works

Optionally drop or select your AZW3 file to inspect its name and size (nothing is uploaded).
Enter the AZW3 filename or full path in the input field.
Optionally override the output FB2 filename (defaults to the same base name with .fb2 extension).
Fill in any metadata overrides: title, author, publisher, or language code.
Click "Generate Command" to produce the full Calibre ebook-convert command.
Paste the command into your terminal (macOS, Linux, or Windows with Calibre installed) and run it.

Use cases

Converting Kindle AZW3 ebooks to FB2 to read on PocketBook, Onyx BOOX, or other Russian e-readers.
Loading personal DRM-free Kindle content into FBReader or other FB2-native apps.
Embedding updated metadata (title, author) into FB2 files before sideloading.
Batch-converting an AZW3 library to FB2 using the generated shell loop commands.
Archiving fiction ebooks in FB2, which preserves chapter structure and author metadata cleanly.
Generating Calibre commands without memorizing all available flags and options.
Verifying your file is actually an AZW3 before attempting conversion (via the file inspector).
Preparing ebooks for reading on devices where FB2 is the preferred or only supported format.

Frequently Asked Questions

Last updated: 2026-10-05 · Reviewed by Nham Vu