In Google Drive, you can use
Sort split-button and choose
Quota Used to show the size of each file there.
However, folder sizes are not shown.
I guess it's really a basic requirement in order to manage folders in Google Drive. I have a folder full of subfolders and files, and I can't go summing up the size of each file recursively.
I need to decide whether deleting this folder or not. But I need to know it's size beforehand.
Is there any way to see how much volume a folder has taken?