How to get output in GB instead of B - powershell

Question

I found a script to check the available space on a remote computer. However I can't find how I can get the output in GB instead of B.
I don't know a lot about Powershell. Can somebody help me adjusting this code so I can see the available free disk space on a remote computer
$disk = Get-WmiObject Win32_LogicalDisk -ComputerName STR3598C -Filter "DeviceID='C:'" | Select-Object Size,FreeSpace
$disk.Size
$disk.FreeSpace

Answer 1

A possible way to achieve this could be to use the following:
gwmi win32_logicaldisk -ComputerName STR3598C -Filter "DeviceID='C:'" | Format-Table DeviceId, MediaType, #{n="Size";e={[math]::Round($_.Size/1GB,2)}},#{n="FreeSpace";e={[math]::Round($_.FreeSpace/1GB,2)}}
Expected output:
DeviceId MediaType Size FreeSpace
-------- --------- ---- ---------
C: 12 215.52 111.1

Answer 2

Another way is to store the results in a variable (like with your code example) and format that for output to screen and/or save it in a CSV file:
$computer = 'STR3598C'
$disk = Get-WmiObject Win32_LogicalDisk -ComputerName $computer -Filter "DeviceID='C:'" |
Select-Object #{Name = 'Computer'; Expression = {$_.PSComputerName}},
DeviceID, VolumeName,
#{Name = 'Size'; Expression = {'{0:N2}' -f ($_.Size / 1GB)}},
#{Name = 'FreeSpace'; Expression = {'{0:N2} GB' -f ($_.FreeSpace / 1GB)}}
# output on screen
$disk | Format-Table -AutoSize
# or save the output as CVS
$disk | Export-Csv -Path 'D:\disksize.csv' -NoTypeInformation
Output on screen
Computer DeviceID VolumeName Size FreeSpace
-------- -------- ---------- ---- ---------
STR3598C C: Systeem 232,79 GB 89,33 GB