$startFolder = "C:\Program Files (x86)\Steam\steamapps\common"

$colItems = (Get-ChildItem $startFolder | Measure-Object -property length -sum)
#"$startFolder -- " + "{0:N2}" -f ($colItems.sum / 1MB) + " MB"
"Folder | Size (MB)"

$colItems = (Get-ChildItem $startFolder | Where-Object {$_.PSIsContainer -eq $True} | Sort-Object)
foreach ($i in $colItems)
{
    $objFSO = New-Object -com  Scripting.FileSystemObject
    $i.FullName + " | " + "{0:N2}" -f (($objFSO.GetFolder($i.FullName).Size) / 1MB) # + " MB"
}