Do I use data if my Wi-Fi is on?

I have an iPhone 6S and I'm almost always on Wi-Fi but I usually keep my data on anyway. I'm on limited data so I don't like using it a lot. And I was really wondering if, even though I have Wi-Fi on and connected, am I still using data in the background?

It depends if the Wi-Fi is actually connected to an access point - either your home router of a public hotspot.

If it is & it's working properly, you do not use any of your mobile data allowance.

When away from Wi-Fi points, any data use such as checking email or web browsing will be via the phone network and use your data allowance. No. Yes you do. From what I understand, if you are getting a good Wi-Fi signal you do not use data, but if you leave it on and the Wi-Fi gets weak, it can kick in to keep you better connected. To not use data, turn it off when using Wi-Fi.

Yes you do.

From what I understand, if you are getting a good Wi-Fi signal you do not use data, but if you leave it on and the Wi-Fi gets weak, it can kick in to keep you better connected. To not use data, turn it off when using Wi-Fi.