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EPUB to FictionBook FB2 converter

EPUB to FB2 uses our ebook engine and writes FictionBook XML, not the repo's our ebook engine extractor.

  • Converted with Ebook engine · input deleted within 24 h
  • Free: 5 conversions a day · 5 MB each
  • Higher limits →

From real runs

What you get — and what changes

  • Container Changed

    The EPUB zip package became a single XML file with a FictionBook root element.

  • Title metadata Changed

    The rich EPUB kept Rich QA EPUB in book-title, while the sparse sample became Unknown in FB2 metadata.

  • Author metadata Changed

    FTC Writer QA was split into FictionBook name fields by our ebook engine rather than preserving the OPF creator string verbatim.

  • CSS Lost

    EPUB stylesheet files disappeared because FB2 stores semantic book XML, not packaged CSS assets.

  • Tables Changed

    Tabular content remained as readable book content but no longer matched the EPUB XHTML table markup.

  • Images Changed

    Image data may be embedded or represented differently in FB2, so inspect binary sections when artwork matters.

Sample conversions

Rich EPUB to FictionBook

Input
API-rich EPUB with OPF title Rich QA EPUB, author FTC Writer QA, chapters, footnote content, one PNG, and a table.
Output
1,976 byte FB2 with FictionBook root, book-title Rich QA EPUB, lang und, our ebook engine program-used metadata, and generated document id.

Feedback Atlas EPUB

Input
Sample EPUB report with no dc:title in OPF, one content XHTML file, a metrics table, bullets, and a block quote.
Output
1,631 byte FB2 with Unknown title and author metadata, showing sparse EPUB metadata carries through as sparse FictionBook fields.

A real EPUB → FictionBook FB2 run

We converted our EPUB sample (5 KB) with Ebook engine on 2026-09-11. It took 380 ms and produced a 2 KB FictionBook FB2 file, 71% smaller than the input. The engine raised no warnings.

Input · sample.epub · 5 KB

EPUB 3.0: 3 content documents, 0 images, EPUB 3 nav, no cover

Version
3.0
Content documents
3
Images
0
Table of contents
EPUB 3 nav
Cover
no cover

Output · sample.fb2 · 2 KB

59 elements, root <FictionBook>, XML declaration present

Elements
59
Root element
FictionBook
XML declaration
yes

First lines of the output

fb2
<?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>antique</genre>
        <author><first-name></first-name><last-name>Unknown</last-name></author>
        <book-title>Unknown</book-title>
        <lang>und</lang>
    </title-info>
    <document-info>
        <author><first-name></first-name><last-name>Unknown</last-name></author>
        <program-used>calibre 6.13.0</program-used>
        <date>11.9.2026</date>
        <id>632b8cc0-9f02-4ab0-bc9f-ac1f6a408c35</id>
        <version>1.0</version>
    </document-info>
    <publish-info>
        <year>2026</y…

Do it yourself

Calibre ebook-convert

bash
ebook-convert in.epub out.fb2

Check the generated title-info block because Calibre may fill missing EPUB metadata with Unknown.

EPUB to FictionBook FB2 by API or MCP

The HTTP API and the MCP server run the exact engine this page uses (Ebook engine); the response carries the same warnings the web converter shows. Check support first with GET /api/v1/pairs?from=epub&to=fb2.

curl
curl -X POST https://filetypeconverters.com/api/v1/convert \
  -H "Authorization: Bearer $FTC_API_KEY" \
  -F "file=@input.epub" -F "from=epub" -F "to=fb2" \
  --output output.fb2
API reference

When this is the wrong conversion

  • Use /convert/epub-to-md when you need clean source text rather than FictionBook XML.
  • Use /convert/epub-to-azw3 for Kindle sideloading instead of FB2 archive workflows.
  • Do not convert to FB2 when EPUB CSS and nav.xhtml must remain intact.

EPUB to FictionBook FB2 questions

Does EPUB to FB2 preserve the EPUB zip structure?

No. Our ebook engine writes one FictionBook XML document, so OPF, nav.xhtml, toc.ncx, and stylesheet files are not retained as separate package members.

Why did my FB2 metadata say Unknown?

The sample EPUB had sparse OPF title and creator metadata. Our ebook engine filled the missing FictionBook title-info values with Unknown.

Can FB2 keep EPUB CSS?

No. FB2 is XML for book structure and metadata, not a zipped website-like package. Visual CSS rules from EPUB are translated or discarded.

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