Originally Posted By: Bob_00001
That is correct. In fact, since my last post, the Free memory has now dropped to 643.3MB and the Used memory is up to 12.16GB, with no new apps installed.

It seems that after deleting a bunch of things, much of the memory didn't really get freed up. I deleted all of my email messages, and the memory usage of the Mail app never changed.

Assuming your email messages are in an IMAP account, they are stored on the iMAP server, not on your iPhone. Deleting them probably resulted in a marginally noticeable improvement in speed when opening Mail but normally would have negligible effect in the Storage use on your iPhone. The growth in Storage usage might be the result of more and larger Swap files, cache files, and other temporary files. Those temporary files are a function of the number of apps that are open at the same time and what specific apps those are, NOT the total number of apps installed on your iPhone. Deleting apps can free up some Storage but most apps are pretty small.

Before performing a full reset there are two lesser steps that might help clean out your Storage.
  1. Restart your iPhone —
    1. Press and hold the Sleep/Wake buttoh on the side or top of your iPhone (depending on the model) until the "Slide to Power Off" slider appears
    2. Swipe the slider to the right to power off your iPhone
    3. When the iPhone has completely powered down Press and hold the Sleep/Wake button until the Apple logo appears on the screen
  2. Reset your iPhone —
    1. iPhone 7 and 7+ Press and hold the Sleep/Wake button and the Volume Down button until the screen goes blank.
    2. Older iPhones — Press and hold the Sleep/Wake buttonj and the Home Button until the screen goes blank
    3. Wait untill the iPhone restarts itself and enter your passcode
  3. If neither of these frees up any memory and since you have good backups then Settings > General > Reset > Erase All Content and Settings


FYI your terminology is confused. Your iPhone has 3MB of Memory (a.k.a. RAM). It has 16GB of Storage (a.k.a. Disk) and your issue is a lack of Storage not Memory. This may seem nit picking but it can lead to misunderstanding.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein