I've got comics in CBZ format with pictures in 2k or 4k pixels tall and when I try converting them to EPUB, Calibre shrinks the pictures to 1k or under, making them very blurry to view on a mobile or tablet. Is there a setting or type of script I can use to convert each picture to its own EPUB page and not have Calibre shrink the picture?

3 Answers 3


When you open the conversion window, before actually starting the process, go to the comic input tab, you will find a box labeled change images dimensions1.

By default, Calibre uses the settings from the page setup tab to select standard output settings for the selected device, this includes that device screen size, to which the images are resized.

By putting a custom value (in your case, the original dimensions of the pictures inside the CBZ files) on the change images dimensions box, you can force Calibre to use these values instead of the preset ones from the page setup tab.

1 - Or something similar: I'm using the italian version, the actual wording may be a little different.

  • I did find out about it, but there's a catch. It seems to be just the recent versions because I couldn't find it in the older ones. It also specifically has to be in the CBZ format first. I don't know what exactly I was doing wrong before. Maybe I had it in PDF or something similar. It was weird. Oct 9, 2017 at 23:51
  • I just checked, and it specifically does have to be CBZ or a explicitly "comic book" format. No other format can be used like PDF I was using. PDF's can't seem to be rendered and screen capped internally in the conversion process. Oct 10, 2017 at 0:01

Try Kindle Comic Converter. Despite its name, it works for all types of readers, and can output EPUB. Be sure to select the generic reader output, enable Color Mode, and select EPUB as the output format.


When running the CLI Calibre tool called ebook-convert, you can specify --output-format=tablet which will not scale any images. I would assume the equivalent GUI option will have the same behaviour.

  • Worked like a charm for me when I wanted to go from ePub to KePub and was confronted with the same problem. In the GUI it is Convert books -> Page setup -> Output profile select "Tablet"
    – saQuist
    Oct 18, 2021 at 6:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.