Making a comic. How to estimate final file size. (KDP has file limit)

Hi @defaultian8i32sjs5p , The PDF Export Compression tab determines the final PDF file size. If you were to set the Compression settings to no downsampling and no compression the resulting file size might be closer to the combined file size of the links and the document overhead.

The default for the print presets is to flatten and downsample any images with an Effective Resolution over 450ppi to 300ppi and to use Maximum quality JPEG compression. With comic book art where there might be a lot of repeating pixels, I would expect the default compression to produce relatively small file sizes.

Your source art is largely irrelevant except in providing enough resolution to pass through or downsample for proper printing resolution. In most cases, it's better to resize component art so that you don't work with enormously bloated file sizes. For designers that work with high-res library art (magazines, etc.) or in your case, it's not necessary or even a good idea to create intermediate size images — you just live with the slight millstone of a document full of big images.

Everything about exporting to PDF for print is about selecting the right export settings, starting wtih the overall PDF standard and then the resolution, color profile, press/ink profile etc. This will scale all images and produce a more or less fixed size output for art-based pages, and it should be easy to get it under the KDP limit.

There are good references on how PDF exports work, and KDP has a rather cryptic page on the settings and standards they prefer. I don't have either on hand, but some of the PDF wizards here will likely throw in a few links. In any case, that's what you need to study to master this step of production for printing, through KDP or anyone else. (Note that most printers and services will have their own specific requirements and preferences; always follow those over generic or other-guy specs.)