SharePoint:To get the size's of the sites

stsadm -o enumsites -url http://site/subsite>File.txt

where file.txt is used to write the data in to a text file
you will get the data in MB's

so how it look like...

<Sites Count="1">
  <Site
    Url="http://url"
    Owner="A\user"
    SecondaryOwner="A\user2"
    ContentDatabase="WSS_Content_DB"
    StorageUsedMB="13756"
    StorageWarningMB="0"
    StorageMaxMB="0" /> </Sites>