The Samsung Galaxy S3 is available with 8GB of internal, usable memory and the option to add a MicroSD card (sold separately) up to 64GB.
From the home screen, swipe down the Notifications bar.
Tap the Settings icon.
Under the More tab, tap Storage.
The total and available storage will be displayed.
To free up memory on your device, delete unwanted pictures, music, and videos by tapping Apps > My Files > Navigate to the desired file > Touch and hold the desired file > Tap to select any additional files > Trash icon > DELETE. Note: Photos and videos can also be deleted through the Gallery.
Remove unused apps by tapping Apps > Touch and hold the desired app > Drag the app to UNINSTALL > Release the app > Tap UNINSTALL.
Clear app data by tapping Apps > Settings > More > Application manager > Tap the desired app > CLEAR DATA > OK.
Store your files on the cloud by tapping the Google folder > Drive.
Purchase an SD memory card to expand your device memory.