I can see how much space I use in my personal account, but for Business account I only see the space used by all users, not just me:
The only way I have found so far is re-installing Dropbox, and I'll have a warning at the beginning of the installation that with how much space I use:
How can I see how much space I am using on my Dropbox for Business account without re-installing Dropbox?
The website isn't more informative:
Opening my local Dropbox folder & get Windows to tell me its size (right click/Properties) won't work as I don't synchronize all my folders.