How to track how much 4G data you've used/spent?

I have an iPhone 5, and I'm curious as to how to know how much 4G data you've spent/have remaining. My friend told me that it was the Cellular Network Data box (Cellular Usage section in the General Settings); is that it? Or does that box represent everything you've used, Wi-Fi included?

You could check the settings of the phone, or you can download an app by your cell phone provider and it may show you your standings for calls, texts, data usage etc.

If you have verizon there's a widget or app you can download that will display all the data you have used. This does not include Wi-Fi

The cellular network data box only counts 3G and 4G, not Wi-Fi.

If you want a detailed count by app, install the free app Onavo Count.

You can also check usage online on your carrier's website, although it won't tell you which app used what.