title_body: Reducing size of e-book on .MOBI file. Or any alternative to .MOBI file for KDP
upvoted_answer: It is not normal that other poeple told me that with the same number of images and 300 more pages his final file is 1.8MG and my file is 4.48MB
  
  That measurement is not reliable and can very wildy based on the image quality and compression potential. Besides, 1.8 mb to 4.5 mb is not a big deal to worry about.
  
  Is there any way to reduce the .MOBI file size??
  
  How are you generating the mobi? Kindle Previewer or Kindlegen actually pack multiple formats into the result. For example Calibre's converter only outputs one format, thus reducing the file size. But as I said, the file size is not really anything to worry about.