Convert CBZ to EPUB
A CBZ file is just a zip of page images — but e-readers want a proper EPUB with reading order, page dimensions, and metadata. Tanko unpacks your CBZ, optimizes every page for your device's screen, and packages a fixed-layout EPUB that Kindle, Kobo, and every modern reading app understands.
Everything happens in your browser: no upload, no queue, no size limit, no watermark. Pick your device, drop the file, download the EPUB.
How to convert CBZ to EPUB in your browser
- Pick the device profile. The profile sets the page size: every image is scaled down to fit that panel and never scaled up, so a 1,000-pixel-wide scan stays 1,000 pixels wide even on the Scribe profile. If your reader is not listed, choose the profile with the closest resolution.
- Set the reading direction. Left to right for Western comics, right to left for manga. The choice is written into the EPUB spine as page-progression-direction, which is the only place e-readers look for it.
- Leave spreads on Auto unless you know better. Auto reads the dimensions of every page from the image headers before decoding anything, splits landscape pages when they are a minority, and leaves landscape-format books whole. Always split and Never split override that decision for the whole file.
- Drop the CBZ and download the EPUB. The file extension has to be .cbz or .zip, but the real format is detected from the bytes. The output takes its title and file name from the input file name, so rename the CBZ first if you want a different title in your library.
What is inside the EPUB tanko builds
The output is a fixed-layout EPUB 3: one XHTML page per image, each with a viewport set to that image's exact pixel dimensions, and the package flagged pre-paginated with portrait orientation and no synthetic spreads. That is the structure Send to Kindle, Kobo firmware, and desktop readers all treat as a comic rather than a text book.
Pages are stored as JPEG at quality 85 regardless of the source format, so PNG and WebP sources get re-encoded. The first page is marked as the cover image in the manifest, and the table of contents has a single entry pointing at page one — there is no chapter detection.
A ComicInfo.xml inside the archive is ignored along with every other non-image file. Series, volume, and author metadata therefore do not carry over; the EPUB title is the file name without its extension and the language is set to English. If you need richer metadata, edit the finished EPUB in Calibre.
How pages are sorted and which files are skipped
Pages are ordered by a natural sort of their full path inside the archive, so page2.jpg comes before page10.jpg without zero padding, and a CBZ split into chapter folders reads folder by folder. The sort is case-insensitive.
Only files ending in .jpg, .jpeg, .png, .webp, or .gif count as pages. Dotfiles, __MACOSX folders, and Thumbs.db are dropped, as is anything else — text files, XML, fonts — that ended up in the zip. If the conversion reports fewer pages than you expected, check whether some images use an extension such as .jpe or .bmp, which are not picked up.
Animated GIFs are decoded to their first frame only, since an e-ink page is a still image. Every accepted image is decoded by the browser itself, so anything your browser can display, tanko can convert.
Read the guide
Frequently asked questions
- What's the difference between CBZ and EPUB?
- CBZ is a plain zip archive of images with no reading metadata. EPUB is a real e-book format: it declares page order, reading direction, page dimensions, and cover — which is what e-readers and Send to Kindle need to display comics correctly.
- Will the pages be optimized for e-ink?
- Yes — pages are resized to your device's exact panel resolution, converted to 16-level grayscale with dithering (what e-ink can physically show), and contrast-corrected so aged scans get a clean white background.
- Do I need Calibre to convert CBZ to EPUB?
- No. Calibre can do it, but it needs a desktop install and per-book settings. Tanko builds the fixed-layout EPUB in the browser tab, and you can still import the result into Calibre afterward for library management.
- Does the EPUB keep the original image resolution?
- Only when the source is already at or below the panel size. Larger images are downscaled to fit the profile, stepping down by halves before the final resample so fine line work does not alias. Nothing is ever upscaled, so choosing a large profile for a low-resolution source just leaves the pages as they are.
- Will the EPUB open in reading apps, not just e-readers?
- Fixed-layout EPUB 3 is a standard format, and any app that supports pre-paginated books shows one page per screen. On a phone or tablet the grayscale dithering is still visible, because the pages were processed for an e-ink panel.
- Do my files get uploaded anywhere?
- No. Conversion runs entirely in your browser — the file never leaves your device. That's also why there are no size limits or queues.
- Is this really free?
- Yes. Single-file conversion with every device profile and every option is free, with no sign-up and no watermarks.