Wondering where all that space on your Android phone or tablet has gone? The DiskUsage app for Android can be used to examine the space usage of the internal EMMC storage or the SD card of your device. It displays the space usage as a treeview and you can click on each block to drill down to the next level in the directory tree.
DiskUsage can be installed from here. Since you typically need this app when you are out of space, the app has been thoughtfully designed to be just a few KB in size!
Tried with: DiskUsage 3.4.2, Android 4.4.2 and Moto G