Calculating ability to capture an object xx feet with a xx mm wide lens...how?

quickjeep

I need to photograph something that is xx feet wide while only being able to stand xx feet away from it. Is there an online calculator that would help me determine whether or not to pick up a different lens for this task?

-Chris

quickjeep

Answered my own question! For those who are interested, check out http://www.tawbaware.com/maxlyons/calc.htm