that someone had posted a link to a site about how to calculate how much yarn is needed for long tail cast ons. I’ve tried the search feature but I’m not finding it! Then again, maybe I was just hallucinating. 
Here’s a link http://www.knittinghelp.com/knitting/basic_techniques/index.php
Here’s another http://knittingatknoon.com/esttail.html
Hope these help!
I think that’s it! Thanks much!
I had the same question and here were some of the very helpful hints:
http://www.knittinghelp.com/knitting/forum/viewtopic.php?t=3846&highlight=
:XX: