One of the difficulties of playing Texas hold'em is that there is a lot of information to assimilate but one of the advantages is that you can play the game with easy access to relevant statistics and odds information. Fortunately, the basic mathematics needed to correctly play Texas hold'em are not overly complex or hard to remember.
Pot Odds in No Limit Hold'em
Your basic mathematical question in Texas hold'em concerns whether the odds of winning are more favorable than the pot odds being offered. That is to say, if the pot is offering you $4 for every $1 you bet, do you have a better than 4-to-1 chance of winning the hand? More info on this in the article about pot odds.
In some cases, the calculation is pretty close and it may seem counterintuitive to fold the hand. For example, you have As 9s and the flop is Ks Jc 3s. There is $100 in the pot and your opponent has bet $30. Your odds of hitting your flush on the next card are around 4-to-1, whereas the pot odds are only a little better than 3-to-1. Do you just toss this big drawing hand?
No Limit Implied Odds
This is where implied odds come in. Let's say you call the $30 and the 4s rolls off on the turn. Now it is your opponent's turn to bet. Will he just check the $130 pot and give you the opportunity to bluff him?
It is more likely that he will take a stab at the pot and hope his pair of kings or whatever he holds is still good. Let's say he throws in $60. Already your pot odds calculation is different. If there is $100 in the pot and its $30 to call but you can expect to win another $60 on the turn, you are looking at over 5-to-1 pot odds. That money is not guaranteed, but it is likely enough to merit a call.
Stack Sizes when Calculating Implied Odds
When you calculate implied odds you have to pay attention to your opponents' stack sizes. If you are up against a player who is all-in or has very little chips left, there is obviously no implied value.
A situation where it is important to take the implied odds into consideration is when you are pondering a call with a small pair. Say that you play $1/$2 no limit hold'em and looks down on a pair of fours on the button. A tight/aggressive player raises to $10 from early position. You both have $200 in your stacks.
You know that you most likely need a set on the flop to win the hand, but if you do get it, you might win a monster pot. The odds of flopping a set are 7.5 to 1 against, which means that you statistically will hit your hand once in 8.5 attempts. So if you call the $10 bet you must have the possibility to win at least $75 in the future (the implied odds). In this situation you do.
But even though you flop a set, it doesn't guarantee you to take down your opponent's stack. Therefore I usually require my opponent to have at least ten times what I have to call in his stack. I think that is a fairly decent standard.
Using Implied Odds Correctly
Remember to be honest with yourself about implied odds. If your opponent never continuation bets and routinely folds when flush cards hit, you cannot count on him giving you the implied odds you need. Base your implied odds calculation on the situation and your opponent.
