For Mac/OSX the default location is
Android Studio on Windows 8:
(in username : please enter valid username)
Install it and restart your Android Studio.
The above steps are similar for win 7 and also same for eclipse.
Update: Windows 10 (similar steps) – pointed out by RBT
This is the sdk path Android Studio installed for me:
I’m running windows 8.1.
You can find the path going into Android Studio -> Configure -> SDK Manager -> On the top left it should say SDK Path.
I don’t think it’s necessary to install the sdk separately, as the default option for Android Studio is to install the latest sdk too.