There are a few different size columns, Size (auto), Size (bytes), Size (KB)... However I find a good solution to that is to enable the Relative graphs behind size and date fields. Check here File displays.
Also you might find this button and script helpful. Its similar to @steje script, but has some differences. calcfoldersizes-setting.
Edit, just realized @steje was over a year ago, not not really what your were asking about.