Is there a way for a user to tell if their Android device is encrypted or not?
On Oreo 8.0.0
Settings → Security &amp; Location → Encryption &amp; Credentials &amp; it shows phone encrypted
Better method
Using adb command adb shell getprop ro.crypto.state ( works on unrooted devices also) returns encrypted or unencrypted
Output examples

Oreo ( Unrooted, encrypted)


Vostro1510 ~ $ adb shell getprop ro.crypto.state
encrypted


Marshmallow ( Rooted, unencrypted)


Vostro1510 ~ $ adb shell getprop ro.crypto.state
unencrypted

Source - Adb command to check if the device is encrypted
Note : Original question refers to Full Disk Encryption which has been replaced by File encryption from Nougat onwards. See this for details
Edit Instead of adb you can install Termux and type getprop ro.crypto.state to get the result - works on unrooted device also