How to be confident mobile data is off I have a mobile package which includes a small amount of mobile data. If you exceed the limit, or use data abroad, the costs can be truly enormous. This has made me paranoid about how to ensure that mobile data is turned off.

My biggest fear is that I am abroad, but then want to check my email when without wifi. I manually turn on my mobile data, check my emails, but then forget to switch it off.

What is the surest way to avoid this scenario? I have seen all sorts of apps on the market that relate to this issue, but none of them do quite what I need. For example there are many apps you can open up and check your data usage... but of course if you don't know that you've left data on, then why would you even go and check? There are also apps where the icon on your screen shows the state as connected/not connected. But they tend to also act as a switch themselves, so it would be far too easy to accidentally switch data on just by touching the icon. What I would really like is some strong visual indicator of being connected, which isn't itself a toggle to switch data on.

Another alternative that I haven't seen yet is something which turns mobile data off when the phone sleeps (and doesn't turn it back on again).

I have a Samsung Galaxy II with Android 4.3. My phone is not rooted, and I don't want it to be (my banking app does not work on rooted phones).

SOLVED: I ended up using mattm's answer as well as using Firelord's suggestion of macrodroid. I used macrodroid to switch off mobile data every time the screen switches off.
The standard Android Settings->"Data Usage" allows you to set warnings and limits for mobile data usage. The screenshot is from Android 6, but I recall having something similar in Android 4.x. 

This won't give you a visual indication of data usage on your home screen, but it will give you a warning (I don't remember what this looks like) and it will cut off your mobile data if you hit the limit. 

The advanced settings also allow you to toggle whether data is enabled on roaming connections.