To find the storage capacity in GB on your iPhone 4, click Settings, General, Usage and then Manage Storage. From here, you will be able to view your storage capacity along with the size of each app and its contents.Continue Reading
Your iPhone must be powered on to view your storage capacity. To turn on your iPhone 4, hold down the Sleep/Wake button, located on the top left of your iPhone.
Unlock your iPhone, and navigate to your settings. Your settings will display as an icon containing grey gears.
In your settings, click the General tab, followed by Usage. At the top of your screen, you will be able to see the number of GBs available to the left and the GBs used to the right. To see how much total storage your iPhone 4 has, add the two numbers together.
Below where your storage capacity numbers are listed are the apps on your iPhone 4, from largest to smallest. If you find that you are running out of storage, scroll through the list of apps on this screen, and delete any unnecessary or unused apps to free up space.