Calculating odds

[RobGW]

What is the correct way to calculate the odds of hitting a draw after the flop? For example, an inside str8 has four outs. Do I calculate the odds of hitting on the turn and the river(5:1) or just the turn(11:1)? Which one do I use to compare to the pot odds?

[taxat]

I believe it depends on whether you intend, at the time you call the flop, to also call the turn should a blank hit.

[fluff]

You only use the odds for 1 card to come (in the example 11:1). The only time you use odds for 2 cards to come is when you or your opponent(s) are going all in at the flop, and hence no more money enters the pot.