SuttaCentral
If you have a word doc (or docx) you would want to just use the built in heading styles to mark the parts that would go into a table of contents. I don’t use MSWord, so I’m not exactly sure how to do it, but if you google msword heading styles that should help.
Here is a test file https://ufile.io/ybl8glnd
Take a look and try running it through Calibre. I believe the default settings should produce a valid table of contents. They do for me.
…(just downloaded the file - can do something only in the evening - thanks provisorically for support anyway!)
My goodness, these answers.
I just read on my kindle. Suddenly I feel so inadequate 
Kindle Paperwhite - mobi/azw3 ← preffered method
books and Documents by Readdle on iPad -epub
Calibre on Desktop (mac)
My guess is that people using things other than e-ink readers are doing so for the convenience of reading something on a piece of hardware they are already engaging with. Beyond that I can’t imagine why they would do that over a printed book. The whole point of e-ink readers is to make things easier on your eyes and make a better physical reading experience.
Partially. But the main reason for me is switching. I very rarely read books cover to cover these days, and am more typically switching between a book, SuttaCentral, a dictionary app, another book, my notes, etc. E-Ink devices are not built for “multi-tasking” which (to me) is inherent to more scholarly reading.
I can understand that. My Paperwhite is great for pleasure reading, but using it as a reference is cumbersome.
I never stopped to think about that, it’s so true.
I have 16 physical books within arms-reach of me, plus my kindle. And I have the physical books nearby because they are what I go to when I want to quickly and easily look something up, research a topic, reference a phrase/paragraph/concept, or just skim a subject. My kindle, which I use daily, nevertheless takes a back-seat unless I am reading a Dhamma or Buddhist book from cover to cover, or a DN or MN sutta from beginning to end.
My kindle, as much as I appreciate it, is no replacement for my physical Dhamma books. But then again, I am a total book nerd. 
Absolutely. They are built for detraction free reading. And, kind of by default, for storing huge amounts of texts. Both of which are solid advantages.
Absolutely! Just depends on what kind of reading you’re doing 
Websites such as BuddhaNet. I can mention some more but however I do not know if they are early Buddhism or not.
Oh, yes. The pdfs there all have encryption. It’s really a shame.
I’m not sure if it would help on those, but there is some software called Briss that allows you to crop pdfs really well. Sometimes without the margins, a pdf is almost readable on a Kindle.
lol so true. 
Here are a couple things that have worked for me (in regard to improving my experience with PDFs on my Kindle):
OR
“K2pdfopt optimizes PDF files for mobile e-readers (e.g. the Kindle) and smartphones. It works well on multi-column PDF files and can re-flow text even on scanned PDF files. It can also be used as a general PDF copying/cropping/re-sizing/OCR-ing manipulation tool. It can generate native or bitmapped PDF output, with an optional OCR layer. There are downloads for MS Windows, Mac OSX, and Linux. The MS Windows version has an integrated GUI. K2pdfopt is free open source software.”
May these “tips” be of benefit to anyone who struggles working with PDF documents on their Kindles. 
Be careful of that site. Malwarebytes warned me of the presence of a trojan virus when I followed the Willus.com link. 
Thanks for the heads-up!
For what its worth, and I not affiliated with that site or developer, that tool has been A+ for me and my experience with it has been flawless.
I recently (a few months ago anyway) upgraded to the latest version with no pings or dings from my antivirus software etc and I use it both on Windows 10 and Linux Ubuntu LTS.
[edit]
Just another thought of reassurance since I wouldn’t want anyone to think that I was linking to any kind of harmful software:
Because it’s open source software, the code is available for anyone to download, review, and compile. It’s also quite mature software that has been in circulation since 2010 with nearly 750,000 downloads. Looking at it’s version history, it seems to receive relatively steady updates from the developer, even as recently as this month (March 2022) with v2.53. It has also been endorsed, at least by the Linux community, and they are known to be quite… fussy.
Anyway, I hope that helps!
So I suppose, as usual on the internet, be wise, savvy, and safe 
Yes, that’s a great tip. Thanks!
I usually read ebooks on my Samsung Android tablet using either the FBReader app or the Librera PRO app.
There is no point even trying to attempt to convert pdfs. Whats worth attempting is converting between epubs and mobis. But basically the entire Buddhist world online needs to to transition their free ebooks to mobi and epub too. Its really important.
It’s not that hard to remove headers and footers with calibre using Regex, as long as you’re not pedantic. It helps if you know a little bit of html or are an excel wizard.
Instructions here
I find the open-source KOReader on Android or any Kindle to be really fast and great for epubs, PDFs. On my paperwhite, it hides ebooks from the Kindle itself so might help to stop the Kindle “reading you”.
Only issue is it thinks its an ereader on Android so you get no multitouch; need to use it differently to most Android apps. Also does calibre syncing, bookmarks, dictionaries, runs on Linux in an AppImage.
However, exercise caution downloading things outside the Play Store (it’s not on the Play Store, only FDroid which is a red flag - even though it is open source. )