View the individual apps cellular data usage.
The app cellular data usage is displayed beneath the name of the app (e.g. App Store 32.7 MB).
To turn cellular data usage on or off for an individual app, tap the switch to the right of the app name.
Exchange ActiveSync accounts are handled separately from other Mail and Calendar accounts. Exchange ActiveSync accounts continue to use cellular data even if cellular data usage for Mail and Calendar are disabled.
To view the data used by system services, tap System Services.
The data usage is displayed to the right of the system service (e.g. Mapping Services 2.0 MB).
Tap Cellular Data (upper-left).
To reset the usage statistics, tap Reset Statistics.