FolderSizes provides a tremendously useful new feature called calculated date/time fields. In this article, I’ll show you how they work and why they’re so beneficial.
Like every other feature in FolderSizes, calculated date/time fields solve a very real problem. In this case, the issue is that Windows maintains last modified, created, and last accessed date/time stamps for folders using a set of rules that ultimately reflect the operating system’s lack of inherent knowledge of what folders contain.
As an example, let’s look at the modified date/time of a specific folder and compare it against what’s presented in the FolderSizes calculated modified date. To do this, start FolderSizes and configure the main window report view so that the Modified (calculated) column is shown. As seen in the screen shot below (click image for a closer look), you can right-click the detail view column header to configure which columns are shown:
Now for our example we’ll analyze the C:\Windows folder with FolderSizes. Below, you’ll see a snippet of the report created by FolderSizes, with the Logs sub-folder highlighted (click the image for a closer look):
Here you can see that FolderSizes presents two modified date/time stamps for each folder – the original modified date/time (as reported by the Windows operating system) and the calculated modified date/time. For this example, I’ve positioned the two columns next to one another (which you can do by dragging and dropping the column headers) so you can easily see that the calculated modified date differs (considerably) from the normal one.
So how are these two values computed and why are they different?
The answer lies in the fact that normal folder date/time stamps must be explicitly maintained by the Windows operating system. If you were to move a file into the Logs folder shown above, for example, then Windows would alter the folder’s modified date/time accordingly. However, if you were to use a text editor to modify a text file within the Logs folder, Windows would know nothing about this operation, and the modified date/time stamp on the Logs folder would remain unchanged.
Contrast this behavior with what is shown in the Modified (calculated) date/time field within FolderSizes. Here, FolderSizes exploits the fact that it knows the contents of every folder and shows a calculated modified date/time representing the most recently modified object in the given file system branch (folder).
This is an extremely powerful capability, allowing you to view and sort folders by deduced (i.e. calculated) date/time stamps that actually reflect their contents.