The filesizes and folder sizes do not match between the web interface and the Finder. This makes it super tough to ensure that all files and folders are in sync... My use case is I have previously stopped synchronizing some folders on my computer with an earlier version of Dropbox, and they exist both online and on my computer. Now I want to delete those folders without having to go through a new sync over a slow connection (some contain tens of thousands of files in subfolders).
I asked support yesterday how to count the items within a folder and they don't have that ability yet... sigh.
Web folder size 7.67MB
Finder folder size 8.1MB
Web file sizes
Finder file sizes