If you have a grandfathered unlimited data plan from your mobile carrier, hold onto it like it's unobtainium. For those of you just now joining the smartphone movement on Verizon or AT&T, you'll have to choose a tiered data plan. Don't worry, though; we're here to help!
The simplest way to track data usage on your Android phone is by using apps from your mobile carrier. Verizon's app is called My Verizon, and AT&T's app is called myAT&T. Both apps provide information on your data usage based on the information stored on their remote systems. Verizon's app also includes a small widget that displays your data usage.
3G Watchdog is a free app available from the Android Market that keeps track of your phone's data usage. It uses the raw data from the phone itself to count data usage.
After installing 3G Watchdog, set your quota, billing cycle, and alert settings.
Once it begins collecting data, a table will appear on the main screen that shows your usage. You'll also notice a new icon in your notification bar that changes colors (green/orange/red) depending on how close you are to reaching your quota. 3G Watchdog also includes a simple widget that provides usage data at a glance.
My Data Manager
My Data Manager, like 3G Watchdog, is a free app that collects data usage directly from your phone. The difference is, My Data Manager provides usage statistics for individual apps on your phone. This is an excellent way to identify which app or apps are data hogs.
After installation, enter the details of your data plan into My Data Manager.
Once it begins accumulating data, you'll see a list of apps, sorted by their data usage. The widget for My Data Manager displays usage data for mobile, roaming, and Wi-Fi.
There you go. Now you can keep track of your data usage so you don't accidentally go over your tiered plan.