Site collection size report

 Add-PSSnapin microsoft.sharepoint.powershell

$SizeLog = "D:\SPSiteSize.csv"

############################################################

$CurrentDate = Get-Date -format d

$WebApps = Get-SPWebApplication

foreach($WebApp in $WebApps)

{

$Sites = Get-SPSite -WebApplication $WebApp -Limit All

foreach($Site in $Sites)

{

$SizeInKB = $Site.Usage.Storage

$SizeInGB = $SizeInKB/1024/1024/1024

$SizeInGB = [math]::Round($SizeInGB,2)

$CSVOutput = $Site.RootWeb.Title + "*" + $Site.URL + "*" + $Site.ContentDatabase.Name + "*" + $SizeInGB + "*" + $CurrentDate

$CSVOutput | Out-File $SizeLog -Append

}

}

$Site.Dispose()