Get Unallocated Space

get_unallocated.ps1

$disks = Get-WmiObject win32_diskdrive ## Gets the list of disks
$partitions = Get-WmiObject win32_diskpartition ## Gets the list of partitions

## Defining Variables
$i = 0
$partitionCount = 0
$myTable = $null

## Scanning Disks and Partitions and their Sizes
foreach($disk in $disks) {
    foreach($partition in $partitions) {
        if($partition.DiskIndex -eq $disk.index) {
            $partitionCount++
            $i += $partition.size
        }
    }
    ## Create object to store the values of the Disk, Partitions and their Sizes
    $myTable = [PSCustomObject]@{
        "Disk Index" = $disk.index
        "Partition Count" = $partitionCount
        "Total Space(MB)" = $(($disk.size)/1mb)
        "Unallocated Space(MB)" = $(($disk.size - $i)/1mb)
    }

    ## Display values stored in $myTable
    Write-Output $myTable

    ## Resetting the variable values
    $myTable = $null
    $i=0
    $partitionCount=0
}