Is 4 gb of data enough for 3 people?

So my family (my brother, my mom, and me) is thinking about switching to Verizon with the unlimited talk, text, and 4 GB of data a month for the 3 of us. My brother and I are getting iPhones, and my mom a different smart phone, but she hasn't decided yet. She isn't much of an internet person so she wouldn't be using much of the data, but my brother and I definitely will be. Is 4 GB of data enough for the 3 of us or should we go with 6 GB? On the plan my brother has right now, he uses usually a little less or a little more than 1 GB a month. I don't have a way of looking at how much data I use because I'm on a different plan than him. I'm just worried that 4GB won't be enough and that my brother and I will use up all the data and not leave enough for my mom. Help?

Added (1). If you take out the 'my brother, my mom, and me' in the parentheses it makes sense so l o l at u bye

First of all, (my brother, my mom, and me) ARE, not is, lol. Ok 4gb should be plentiful, you can always use Wi-Fi when its avaviable which means you WON't use your 4gb of data, a friend of mine does that and he has 2gb data, and he has barely used 1gb since he uses Wi-Fi instead

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