Free online EPUB to CBZ converter

Some comic-reading apps and devices accept CBZ archives but not EPUB books. Converting an EPUB for those readers means rendering its pages as images and placing them in a CBZ archive, so text and reflowable layout are not preserved.

What the EPUB format is

EPUB is an ebook format built from web technologies such as HTML and CSS, packaged with images, fonts, and metadata. It is used for novels, textbooks, and illustrated books; ebooks exported from word processors or created with tools such as Sigil and Calibre are often EPUB files. Many EPUBs reflow text to fit the screen, while some use fixed layouts.

What the CBZ format is

CBZ is a ZIP archive of sequential image files, commonly used for digital comics and supported by many comic readers. It presents each image as a page and is suitable when a reader requires image-based comic files. Page images can be JPEG or PNG; the filename order determines reading order in many apps.

How to convert EPUB to CBZ

Online on 101convert.com

1. Open the EPUB-to-CBZ converter on 101convert.com and upload the EPUB file.
2. Select CBZ as the output format and start the conversion.
3. Download the converted file when it is ready. Multiple files can be converted in one batch; the page shows the per-file size limit.

Offline with desktop software

A free, open-source workflow uses Calibre, Poppler, and Python. Calibre (Windows, macOS, and Linux) renders the EPUB to PDF; Poppler creates page images; Python packages them in the correct numeric order.

1. Convert the ebook to PDF with Calibre’s command-line tool: ebook-convert book.epub book.pdf. In Calibre’s interface, use Convert books → Output format: PDF. Check the PDF’s page size and margins before continuing, since these determine the image dimensions and whitespace.
2. Install Poppler, then render the PDF pages as PNG images at the chosen resolution. For example, pdftoppm -png -r 150 book.pdf page creates files such as page-1.png. Higher resolution retains more detail but increases the CBZ size.
3. Save the following as build_cbz.py in the folder containing the page images, then run python build_cbz.py:

from pathlib import Path
import re
import zipfile

pages = sorted(
    Path(".").glob("page-*.png"),
    key=lambda p: int(re.search(r"-(\d+)\.png$", p.name).group(1))
)
with zipfile.ZipFile("book.cbz", "w", zipfile.ZIP_DEFLATED) as archive:
    for page in pages:
        archive.write(page, page.name)

Quality and limitations

EPUB-to-CBZ conversion changes ebook pages into images. The resulting CBZ does not retain selectable or searchable text, EPUB navigation, or reflow; text may be less readable if the PDF page size or render resolution is too small. PNG avoids additional image compression but can produce large archives. Review the rendered PDF before making the CBZ, especially for fixed-layout books, where page dimensions and artwork placement matter.