DontUnderstandMyIpad said:Due to the nature of iOS, where all apps run sandboxed, they cannot interfere directly with each other, so it is not possible for an app to give an overview of all the other installed apps, nor the size of each app.
However, when the iPad is connected to your computer, you can open iTunes, select the iPad and then in the Apps tab, change the viewing to "Sort by size". That will organize all apps by their size, even the ones not currently installed.