Does using my iphone on Wi-Fi add data towards my 3GB monthly plan?

I have the iphone 5 on AT&T 4G LTE. I have an app called "My Data Summary" which shows me my daily usage of data.So, I switched from 4g LTE to my home's Wi-Fi. The app also shows how much data i use on the Wi-Fi as well. I'm just wondering if when I use my Wi-Fi, does that data also add on or not?

Wi-Fi does not count against your data limit.

As long as you're on Wi-Fi, you can browse as much as you want. Contact you phone/TV/Internet company to see what your Wi-Fi rate plan is. Some people have a 15GB limit, for others it's unlimited.

As for your mobile data (4G LTE) your usage towards it will count when you are not connected to Wi-Fi.

Hope this helps.