Does watching videos on youtube take up monthly data on an iphone if you have Wi-Fi?

Does watching videos on youtube take up monthly data on an iphone if you have Wi-Fi?

If it's using your data band then yes, if it's using your Wi-Fi then no, you can download a toggle widget for switching off data, forcing it to only use your Wi-Fi, that's what I use.

If you use the Internet with anything on your phone, while not having Wi-Fi on, it uses data. You are fine.

No, if you are connected to a Wi-Fi connection, then NO it won't use your Data connection.

No, it does not take up any data whatsoever as long as you are on Wi-Fi