The majority of my ebooks are from Amazon, Kobo, Google Play and Smashwords. Only those I'm actually interested in and might potentially read one day. But I don't just add any ebooks to my library. Certainly I have no hope of ever reading them all, I'm not a particularly fast reader. I have several thousand ebooks in my library, downloaded/purchased from many different places. If it were number based, then try and combine some documents, and see if that helps. Combining both though would be the simplest way to kind of emulate the Kindle Storage you have been doing.

You can even tee things up with calibre backups, though I believe the backups need to be zipped to overcome some naming issues, with one or more cloud services. However, because they are yours, you can use whatever cloud service you wish (Dropbox, Google Drive, etc). When it comes to personal documents though, they don't get that choice, and each needs to be stored. (even though my hopes for a useful reply are quite low)Д¬learly these documents of yours don't have DRM, and 1199 seems an almost arbitrary number, so perhaps it is size of storage rather than number of files.Д¬ertainly many of us have a lot more ebooks on our Kindles than that, but most are probably Kindle ebooks and thus not really stored in space allotted to us, but in generic server housing, because many have the same ebook and it would be waste to store that same ebook many times (thousands, possibly millions in some cases). The rate I am going I should be there within the next 1-2 years.

So I'll have to figure out something if that is the max number. I don't use it to send stuff to my kindles either. I only go into it every 2 months or so to backup my purchases from amazon, that is about it. Its always there, while calibre is on a computer I'd have to start up first and all that.

The kindle cloud is much more easy accessible to me than calibre. Its mostly recipes and things like that and some books I bought elsewhere. My docs should go back for as long as I had kindles, 2008.ДЄs it shows now since 2011, I am not above that threshold yet mentioned in the OP. I can't recall when the send to kindle add on thingie came about, but I used to use the email address back in the day. But I know that I have send many before that via the email option. Does anyone remember when they changed the way docs were stored in the account? I looked into my a count and all docs start at 2011.

Kindle personal documents page