How can I tell when data is being used?

[somervillesis]

I have only a basic understanding of what data usage is (namely that it involves the consumption on content via the internet and your phone and that you pay for a certain amount per month). I usually have a low data usage amount but have had two months where I soared to my limit and I don't know why. So I am confused about my rate of data usage and how I can control it.

How can I tell if I am using data?

Is there a way for me to be notified when I am using data?

Is there a way for me to stop apps or other services that may be using data?

Is data usage related to wi-fi vs 3G/4G?

I have a Samsung Galaxy S4.

[Salisbury]

How To Monitor Your Data Usage On Your Samsung Galaxy S4 - Phones 4u - YouTube

[tikibar1 · Accepted solution]

9 ways to stay below your data cap on Android and iOS | TechHive

How to Minimize Your Android Data Usage and Avoid Overage Charges

[mama23dogs]

If your phone was recently updated to lollipop OS. It may not be connecting to your wifi, or have some other network errors. 

Resetting network settings may help. 

Delete and add back your wifi connections. 

In some cases replacing SIM cards, or resetting the phone to factory settings and setting it up again fix the problem.

You can test wifi connection by turning off mobile data to see if internet still works well over wifi.

if the problem persists, please take your phone in for repair.  It is frequently an easy fix.

[tikibar1]

The Galaxy S4 hasn't received Lollipop yet. 

Your post reminded me of something else the OP can check, though:

Settings > Wi-Fi > Menu (the three dots in the upper right-hand corner) > Advanced > Keep Wi-Fi on During Sleep > Always

[stef7]

The URL that Salisbury posted to the YouTube video is very good. But it omits an additional feature of the monitor... the monitor can also track WiFi usage. At least on the LG G2 it is capable of doing so. Verify this on the S4.

After going into Settings | Mobile Data, select the Menu key, and check "Show WiFi Usage".

Now when you go into Settings | Mobile Data, you'll see two tabs, one for Mobile and one for WiFi. You can select the tab you are interested in seeing the results.

When you suspect your device is using either radio a lot, this is a great tool to diagnose what program is using that bandwidth, either Cellular Radio, WiFi (or both).

[tikibar1]

stef7 wrote:

The URL that Salisbury posted to the YouTube video is very good. But it omits an additional feature of the monitor... the monitor can also track WiFi usage. At least on the LG G2 it is capable of doing so. Verify this on the S4.

The ability to track wi-fi usage is available on the S4.