It is very close to full.
A 16 GBs iDevice starts off with about 13 GBs after formatting and installation of iOS.
iOS needs between 2-3 GBs of storage space to operate at an acceptable, nominal performance level.
This leaves you about 10-11 GB of internal free data storage space.
You cannot fill up storage on any computer or computing device.
You have reached pretty close to that limit.
This is why Apple no longer sells 8 and 16 GBs storage iDevices, any longer.
These devices have to little internal free data space to work with or do much of anything with.
If you need to free up free data storage space on an iPad/iDevice, you need to start by backing up your iPad to
either Apple's iCloud or by connecting your iDevice to a computer running the latest iTunes or some other offsite,
“cloud” data storage service, like Google Drive/Photos, DropBox, Box, etc.
Then, delete any installed apps that you no longer use or use infrequently enough that they aren't missed ( you can always reinstalled any purchased or free apps at some time later, as you need them ).
Thin out/delete any music/videos/movies/TV shows/images/eBooks/eMagazine/iBooks/audio books/Documents/PDFs, etc.
If you use a POP email account on your iPad, delete/thin out any old saved emails that maybe saved to your iPad.
To permanently delete photos/images off of your iDevice, go into the Photos app and find the Recently Deleted folder/album and permanently delete any photos/images stored in that folder/album.
Also, you can check to see what stuff is eating up all your valuable data storage space by going into the Settings App,,General Settings Panel, in the right hand column, tap Storage & iCloud usage panel ( in iOS 11, it’s iPad Storage ), in the top Storage Panel, tap the Manage Storage panel, wait for a list of apps to generate that will tell you how much space each app is taking up on your iDevice.
Then, do a hard reset of your iPad by holding down both the Home and sleep/wake buttons simultaneously until your
iPad goes to black and restarts with Apple logo, then release the buttons.
iDevices need to maintain, at the very least, a minimum of between 2-3 GBs of free data storage space, at all times, to insure normal/nominal functionalities/operation and general overall performance of any iDevice.
Best of Luck to You!
