How to Check Your iPhone's Data Usage
How-To: Check Your iPhone Data Usage
Wondering just how much data you're pulling down in a given month on your iPhone? There are a few ways to check your usage, one being to head to AT&T's wireless website, log into your account, and AT&T, Verizon, or by signing in to your Sprint account.
However, this third way only requires you and your iPhone to see how much data you're devouring. Find out what to do after the break.
Since existing customers can keep the plans they're on now, you can reset your statistics today (by hitting the "Reset Statistics" button at the bottom of the screen), and check back next week to estimate just how much bandwidth you're eating up each month, and determine if you want to switch to a less expensive plan.
Source: Apple