CBT (comic TAR)
Also known as: .cbt file, comic book TAR, comic archive TAR
CBT is a comic-book archive that is simply a TAR file of page images renamed with a .cbt extension. Comic readers open it, sort pages by filename, and display them in order — the same idea as CBZ but using TAR instead of ZIP.
- Comic archive: a TAR of page images
- Same idea as CBZ but uses TAR, not ZIP
- TAR adds no compression; size = sum of pages
How CBT works
A .cbt file is an ordinary TAR archive containing the page images (usually JPEG or PNG) in reading order. Rename it to .tar and any archive tool will open it; comic apps read it directly.
It is one of the comic-archive family — CBZ uses ZIP, CBR uses RAR, CB7 uses 7z, and CBT uses TAR. CBT is the least common of these because TAR alone adds no compression.
Files and storage
Since TAR does not compress, a .cbt is roughly the combined size of its images. A long, high-resolution color comic can run to tens or hundreds of megabytes, while a short issue stays small.
CBT and CBZ files are interchangeable in most readers, so there is rarely a reason to choose CBT specifically. The images inside drive the file size.