Feuerfest

On my gaming PC Windows complained that C:\ had only 10GB of free space left. Time to free up some space! In WindowsXP times I used a separate Program called GetFolderSize for this, but nowadays with PowerShell I was like: "Hey, I bet I can do this with PowerShell alone."

After a bit of back & forth I came up with the following function:

function Get-FolderSize {
    param([string]$Path = ".")
    Get-ChildItem $Path -Directory | ForEach-Object {
        $size = (Get-ChildItem $_.FullName -Recurse -File -ErrorAction SilentlyContinue |
                 Measure-Object -Property Length -Sum).Sum
        [PSCustomObject]@{
            Folder = $_.Name
            "Size(MB)" = "{0:N2}" -f ($size / 1MB)
            "Size(GB)" = "{0:N2}" -f ($size / 1GB)
        }
    } | Sort-Object { [double]($_."Size(MB)") } -Descending | Format-Table -AutoSize
}

It worked fine. However I always needed to copy & paste it into the current PowerShell window to have the function available. Hence I had a new question: How do I make this function available for my local Windows? How do I add this function to the PowerShell equivalent of a .bashrc?

I myself was surprised I didn't know how to do this. Never needed it before apparently. And at customers PowerShell and/or UserProfiles are always locked down so that I can't do such stuff.

Making a PowerShell function constantly available

Microsoft has some documentation available about the $PROFILE variable: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_profiles?view=powershell-7.6

First I tested if I already have a $PROFILE for the current user on the current host. This turned out to be false:

PS C:\Users\USER> Test-Path $PROFILE
False

Hence I simply create the $PROFILE:

PS C:\Users\USER> New-Item -ItemType File -Path $PROFILE -Force


    Verzeichnis: C:\Users\USER\Documents\WindowsPowerShell


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a----          8/8/2026   4:44 PM              0 Microsoft.PowerShell_profile.ps1

Now I can edit my $PROFILE and the Get-FolderSize function:

PS C:\Users\USER> notepad $PROFILE

Then just copy&paste the function in the Microsoft.PowerShell_profile.ps1 file:

After that we need to source the $PROFILE again to have it available. Just like on Linux:

PS C:\Users\USER> . $PROFILE

And it works just fine:

PS C:\Users\USER\AppData> Get-FolderSize .

Folder   Size(MB)  Size(GB)
------   --------  --------
Local    53,609.24 52.35
Roaming  10,956.81 10.70
LocalLow 9,207.82  8.99

Alternatives

PowerShell Gallery

Only later did I learn of the site https://www.powershellgallery.com/, they collect scripts from the community and make them available. There seems to be a good script here, however I didn't use it.

Microsoft SysInternal DiskUsage Utility

There is a du tool from SysInternals available here: https://learn.microsoft.com/en-us/sysinternals/downloads/du. Downloading that and putting the binary in the $PATH should do the trick to. However I did not check if the output matches my desired format.