Onavo looked into AT&T’s new Mobile Share Plan and found that typical smartphone users will be forced to face higher monthly fees, which could cost them $300 more per year.

Typical US smartphone users consume around 300 MB of data a month and don’t pay for unlimited calling. With the new Mobile Share plans, smartphone users are being forced to pay more for services they don’t need.  Most people don’t understand what a megabyte is, let alone how many they will need a month. The new plan may look attractive, but our analysis shows that the average user will unwittingly be paying AT&T as much as $300 more per year.

Onavo has created a helpful guide that pits the total cost of the Mobile Share plans against the old plans for users with typical consumption: