CBZ and CBR files: what they are and how to open them

A file ending in .cbz is an ordinary ZIP archive whose contents are the pages of a comic or manga volume, one image per page. The extension stands for Comic Book Zip; the different suffix exists so a comic reader can claim the file type without also claiming every ZIP on your computer. The convention dates from the CDisplay reader in the early 2000s.

A .cbr file is the same arrangement of page images inside a RAR archive, which was the scanning community's default archiver for years. The catch is that RAR is proprietary: creating one requires WinRAR or the official rar tool, and reading one requires unrar code that many programs never included. ZIP support is built into every operating system; RAR support is not.

Two rarer siblings follow the pattern: CB7 is a 7-Zip archive of images and CBT is a tar archive. Plenty of readers skip both, and repacking either as a CBZ takes a minute with 7-Zip.

None of these containers was designed as a book format, so nothing in the ZIP or RAR specification says which image is the cover, which way the book reads, or what the series is called. Readers infer the order by sorting file names, which is why a well-made archive uses zero-padded numbers such as 001.jpg and 002.jpg, and why a badly named one displays out of sequence.

The closest thing to a metadata standard is ComicInfo.xml, a small file defined by the ComicRack application and now written by tagging tools such as ComicTagger and read by library servers such as Komga and Kavita. It is a de facto convention rather than a standard: many archives have none, the schema has drifted between tools, and e-readers ignore it entirely.

The apps below are actively maintained as of 2026, free or inexpensive, and open a CBR without extra setup.

Extensions are a promise, not a guarantee. A .cbr that a reader refuses to open is often a ZIP that someone renamed, and the reverse happens too.

Kobo lists CBZ and CBR among its supported formats, so on a Clara, Libra, or Elipsa you can copy the archive over USB and open it from the library. It works, with limits: each page is decoded from the full-size scan on a slow processor, so a large archive turns pages more slowly than an EPUB. Converting to a fixed-layout EPUB sized for the panel is optional on a Kobo but usually lighter and quicker.

Kindle firmware has no archive reader and Send to Kindle rejects CBZ and CBR outright. The working path is to turn the archive into an EPUB and deliver that.

Tanko is the converter behind the pages linked below, and it runs in your browser: a Web Worker on your own machine opens the file, and nothing is sent anywhere. Use it when the destination is an e-reader, whether a Kindle that cannot open the archive at all or a Kobo you want to feed a smaller, pre-sized book. It is not a reader; for that, pick one of the apps above.

Here is what it does, and only this. It identifies the container from the first bytes, so a mislabeled file still converts, and it accepts ZIP and RAR, with RAR4 and RAR5 both read by a WebAssembly build of unrar that loads only when a RAR is dropped. It skips every entry that is not a JPEG, PNG, WebP, or GIF, including ComicInfo.xml, dotfiles, and macOS resource folders, then orders the pages by a natural sort of their full path. Each page is scaled down to the Kindle or Kobo profile you pick, processed for e-ink on the grayscale ones, and written into a fixed-layout EPUB with the reading direction you set. CB7 and CBT files, password-protected RARs, and multi-part RAR sets are rejected; repack those as a plain CBZ first.

A comic page scanned at 300 pixels per inch is roughly 2,000 by 3,000 pixels and weighs 1 to 3 MB as a good-quality JPEG. Multiply by 24 pages for a single issue or 200 for a manga volume and the archive lands anywhere from 30 MB to well over 500 MB. The container barely matters, because JPEG data is already compressed and ZIP or RAR shaves off only a percent or two.

That size is why conversion helps on an e-reader even when the device could open the original. A 6-inch or 7-inch e-ink panel shows at most about 1,264 by 1,680 pixels, so every pixel beyond that is decoded, scaled, and thrown away on each page turn. Resizing once, ahead of time, produces a much smaller book that renders without a pause.