Get folder sizes with recourse. The output is list of first level directory structure under specified path.

Get-FolderSize.ps1

Function mms-FolderSize {
    <#
    .Synopsis
    The function will return folder size and list of first level subfolders size.
    
    .Description
    The function is simmilar to reskit command "diruse" or unix tool "du". The output is sum value of file sizes 
    in specified folder and summary siza for each first level subfolder. The function is build up on top of 
    get-childitem function.

    .INPUTS
    -Path <[System.IO.FileInfo]string> -ShowIn [B,MB,GB]

    where paramter path:
        - is default parameter, not mandatory.
        - if present, function will run in the specified path (if exist)
        - when paramater is missing, current folder is set
        - an alias is "p"
    
    parameter ShowIn:
        B  - the default parameter represent not formated output of get-child item in bytes (as Int)
        MB - represent formated output (string) in MegaBytes, sorted decreasing
        GB - represent formated output (string) in GigaBytes, sorted decreasing

    .OUTPUTS
    The default output is:
    [String]Path
    [Int]Size - when "ShowIn" param is missing, or
    [String]Size - formated Int output with expression "{0:N2}"
    
    .Example
    List of current folder size and subfolder sizes:

    PS C:\Temp> mms-FolderSize

    Path                                                                       Size
    ----                                                                       ----
    C:\Temp                                                                  935494
    C:\Temp\Microsoft Visual C++ 2010  x...                                       0
    C:\Temp\Microsoft Visual C++ 2010  x...                                       0
    C:\Temp\pulse                                                          20924852

    .Example
    List of current folder size and subfolder sizes formated in MB

    PS C:\Temp> mms-FolderSize -ShowIn MB

    Path                                                                    Size (M
                                                                            B)     
    ----                                                                    -------
    C:\Temp\pulse                                                           19,96  
    C:\Temp                                                                 0,89   
    C:\Temp\Microsoft Visual C++ 2010  x64 Redistributable Setup_10.0.40219 0,00   
    C:\Temp\Microsoft Visual C++ 2010  x86 Redistributable Setup_10.0.40219 0,00   

    .Example
    List of specified path subfolders size, formated in MB

    PS C:\> mms-FolderSize C:\RecoveryImage -ShowIn MB
    PS C:\> mms-FolderSize -p C:\RecoveryImage -ShowIn MB
    PS C:\> mms-FolderSize -path C:\RecoveryImage -ShowIn MB

    Path                            Size (MB)
    ----                            ---------
    C:\RecoveryImage                2 816,05 
    C:\RecoveryImage\Drivers        672,57   
    C:\RecoveryImage\OEMInformation 0,21     

    .Example
    The example of piped folder with manual expression and sorting

    PS C:\>$env:systemroot | Get-FolderSize | 
        sort size -Descending |
        select -First 10|
        format-table Path, @{Name="Size (GB)";Expression={"{0:N2}" -f ($_.size / 1GB)}} -AutoSize

    Path                     Size (MB)
    ----                     ---------
    C:\WINDOWS\WinSxS        6,11     
    C:\WINDOWS\System32      3,52     
    C:\WINDOWS\SysWOW64      1,20     
    C:\WINDOWS\assembly      0,85     
    C:\WINDOWS\Microsoft.NET 0,67     
    C:\WINDOWS\Fonts         0,59     
    C:\WINDOWS\Globalization 0,20     
    C:\WINDOWS\IME           0,16     
    C:\WINDOWS\Panther       0,14     
    C:\WINDOWS\Speech        0,12     

    .Notes
    Last Updated: January 29, 2015
    Version     : 1.0

    .Link
    #>
 
    [cmdletbinding(DefaultParameterSetName = "Path")]
    Param(
        [Parameter(Position=0, ValueFromPipeline=$true, ValueFromPipelineByPropertyName, ParameterSetName="Path")]
        [Alias("p")]
        [String]$Path = $null,
        
        [parameter()]
        [ValidateSet('B','MB','GB')]
        [String]$ShowIn
    )

    Function Get-Sizes {
            $obj = new-object psobject
            add-member -inp $obj noteproperty Path $path
            $size = (Get-ChildItem $path -ErrorAction SilentlyContinue | Measure-Object -Sum Length -ErrorAction SilentlyContinue).Sum
            if ($Size -gt 0){add-member -inp $obj noteproperty Size $size} 
            else {add-member -inp $obj noteproperty Size "0"}
            $obj
            get-childitem $path -ErrorAction SilentlyContinue | where {$_.PSIsContainer} | foreach {
                $obj = new-object psobject
                $size = (Get-ChildItem $_.FullName -recurse -ErrorAction SilentlyContinue| where {!$_.PSIsContainer} | Measure-Object -Sum Length).Sum
                add-member -inp $obj noteproperty Path $_.fullName
                if ($Size -gt 0){add-member -inp $obj noteproperty Size $size} 
                else {add-member -inp $obj noteproperty Size "0"}
                $obj
            } #foreach
    }#function get-sizes

    if (!$path){$path = Get-Location}
    if (test-path $Path) {
        If ($ShowIn.ToUpper() -eq 'MB'){get-sizes |sort size -Descending |ft Path, @{Name="Size (MB)";Expression={"{0:N2}" -f ($_.size / 1MB)}} -AutoSize}
        elseIf ($ShowIn.ToUpper() -eq 'GB'){get-sizes |sort size -Descending |ft Path, @{Name="Size (GB)";Expression={"{0:N2}" -f ($_.size / 1GB)}} -AutoSize}
        else {Get-Sizes}
    }  else {Write-Output ('Path "'+$Path+'" Does not exist')}

} #function mms-foldersize

#mms-FolderSize c:\users #|sort size -Descending |ft Path, @{Name="Size (MB)";Expression={"{0:N2}" -f ($_.size / 1MB)}} -AutoSize