?How do I know how much space really occupied an app?

[Mexican WPLover]

Long time ago I saw an article about an app that let you now how much space really requires an app, but I can't find it. Anyone know what's is name?
Sorry for the bad English.

 

[realwarder]

re:

Settings, storage sense

 

[Mexican WPLover]

But I mean before installing the app (I forget to specify) it was an app that let you know how much space will occupied an app after installing it