Is 3GB of Data Enough for 2 people on iPhones?

Me and my brother are getting iphones.
if we do 3GB of data, would that be enough for moth of us mixed together?
also, i know about using Wi-Fi when its there, so of course i won't use the GB when there's Wi-Fi.
also, is 3GB more than MB? And more than 1gb? Sorry i'm stupid…
thanks:-)

Added (1). Its iphone 5 by the way

Your not stupid, unless your computer savvy, you wouldn't know this. 1 GB (gigabyte) is equal to 1024 MB (megabytes). A larger number of GB or MB is larger. Depending on what you use your data for when you are away from Wi-Fi would make it enough or not enough. I can't tell you since I don't know what you want to do with it. Unless you are watching a lot of pictures or videos on the data, then 3 GB should be plenty sufficient. There's a way to check your data usage in your phone settings, I would start with the 3 GB plan and use it as much as you would normally, and watch to see how fast the data usage goes up. Just be aware of when you get to the end because when you do it is rather expensive overage fee.

Yes more than enough but it really depends how long your on the website for 3gb is more than mb and 1gb look here:
1024KB in 1MB
1024mb in 1GB

Unless you watch things like Netflix all the time 3GB would be enough for 2 people. 3GB= 1000MB