File Size when converting CBZ to mobi?

[Ito]

I have a question about the files size of things when I convert files in calibre.

I have been reading manga on my kindle for a while. I use mangle to convert all the images and just putting the files over in a picture folder. It has been mostly fine, but that just means I can't use calibre to manage them.

I tried converting them to .pdfs, but I felt like the quality went down a bit and my Kindle DX displayed them kind of "jaggy"

So I no tried throwing all the images into a zip. Renamed the extension and popped it in to calibre. The file size before converting was 25.6mb (it was 26.1mb before zipping). After converting it to mobi, the file size jumps to 45mb, which is a huge increase. I have played around with the settings, but they all seem to output files with roughly the same size.

The larger sizes mean I can have substantially less content on my kindle and that my manga library will take up almost twice the space that it used to. Is there something that I can do in the settings to help this? Or why does it just jack up the file size so much?

Thank you to anyone who can comment on this!

[kovidgoyal]

Look under MOBI output in the conversion dialog, use the checkbox to not convert images to jpeg

[Ito]

Yup, that was it!
Thank you so much for your help!