Texas Hold'em Odds
"Outs" are unseen cards that will make any hand you expect will win the pot if they come off on the turn or river. There are 47 unseen cards on the flop. To determine your odds of making your hand, you divide your number of outs by the remaining unseen cards (that will not help your hand). An outside straight draw has 8 outs. 47-8 is 39 cards that will not help you. 39 ? 8 = 4.88. Your odds are 4.88 to 1 to complete your straight draw on the turn. On average, you will catch your straight on the turn 1 time for every 4.88 times you miss. This draw is profitable if you are receiving the proper pot odds to call. If you have to call one small bet, and there are five small bets in the center plus your opponents bet makes your pot odds 6 to 1. It is clearly profitable to call a bet with 6 to 1 payoff odds when you have 4.88 to 1 odds to make your hand. You should at least call on the flop any time the pot odds are offering you greater odds than the odds that you will make your draw.
Below is a chart that gives your odds of drawing out in % and X to 1 odds for the number of outs you believe will give you any hand that will win the pot. Your odds for drawing one card on the flop and one card on the turn are the only numbers that matter to you. The % and X to 1 odds for drawing on both the flop and turn are included only for completeness sake. You only consider your odds of taking one card off at a time. You do the math and decide if a call on the flop is profitable, then if you do not complete your draw, you completely reevaluate the situation when you make a decision on whether or not to call on the turn with your draw.
Complete odds of drawing out in % chance and X : 1 odds for drawing on the flop and/or turn.
[ You can also read the Party Poker Strategy Guide's article on poker odds as well, for a full treatise on how to calculate and work with odds. ]
You can see that a pocket pair that misses on the flop usually only has 2 outs to beat a bigger pair and 22.5 to 1 odds to catch and make a set on the turn. That means that the pot must have 23 small bets in it to get proper odds to call with a pocket pair that misses. That is why you almost always lay down a pocket pair that misses when there are overcards because the chance to improve is very small. The most common draws are flush and (outside) straight draws, and they only need pot odds of 5 to 1 to make chasing with them profitable as long as they will make the best hand if they catch. There are many other types of draws such as a hand that has paired the board with 5 outs to pair your kicker or make trips, but these types of draws are usually not advisable unless the pot is offering very good odds, because you could be wrong about the strength of your opponent's hand, and even if you are right, your opponent might have a good chance to redraw against you.
Ideally, you would like to call a single bet with a good draw to the absolute nuts in a big pot. This of course is seldom the case, so you have to use your judgment in counting the outs that will give you any hand that will win the pot. If you have Ah Th and the flop is Kh, 8c, 4h, you have 9 outs (unseen hearts) and 3 more (Aces) if you believe you are up against an opponent who has paired the king and if you hit your ace, you will indeed win the pot. If you think your opponent has a hand that a pair of aces will not beat, you should only count the 9 hearts as valid outs.
If you will have a very good draw you can bet or raise for profit if you expect to get enough callers to make your bet or raise profitable. For instance, you have Qh Jh in late position of a multiway pot, and the flop comes 2h Kh Tc. An early position player bets and two players call in front of you. Any heart gives you a flush and an A or 9 gives you the nut straight, that is 15 outs (don't count the Ah and 9h twice). Your odds of making one of these hands on the turn are 2.13 to 1. You can raise in this situation because you will be getting 3:1 odds on the raise if all players call. This is a perfect example of a good place to raise for profit. You should bet or raise for profit when you expect to have enough callers to give you better payoff odds than the odds you will make your hand.
Sometimes it may be profitable to call with a hand that does not have the necessary pot odds according to the odds of the draw. You can usually count on additional bets going into the center on the turn and river if you make your hand so you expect that the pot odds that will be offered by the showdown will be greater than what is offered on the flop. That is why it can sometimes be profitable to draw on the flop with an inside straight draw to the nuts when the pot is big, even if it is not quite offering correct pot odds. If you expect additional action on later streets, you can factor that into your decision to call on the flop. This is often referred to as implied odds.
Sometimes it will be difficult to estimate future action and calculate accurate implied odds to determine if your draw is mathematically worth a call on the flop. You can usually count on at least two more big bets (single opponent's call on turn and river), but you will often get more action, especially in a multiway pot.
A good way to look at this is to determine the odds for your draw, and see how big of a pot you need to call. You should call if you expect the pot to eventually reach that size should the card you need come off on the turn. You cannot be sure that you will indeed get the additional action you need for hand to be worth a call, so you should be conservative in your estimations. If there are more active players to act behind you, you must be prepared to call a raise as well. You should adjust your pot odds to having to call a double size bet if you suspect you might see a raise behind you. Poker is about people, and the better you can read opponents, the more accurately you can predict their hands, their actions, and the profitability of your play against them.
You do not want to be drawing for a straight or flush with a pair on the board. Someone could already have a full house or quads and you could be drawing completely dead. [MJ: This is very conservative strategy and often you don't need to worry about the full house]. You have no hand at this time, and you do not want to put any money in to chase when you could make your draw and still lose the pot. Furthermore, don't draw at a straight with a two flush on the board, unless the pot is big enough to justify your drawing with only 6 outs instead of the usual 8 (two of your straight cards will bring the flush). It is somewhat different when you have a completed hand like a flush or straight and the board pairs possibly giving an opponent a full house. You do not automatically stop betting, but you should now be very cautious because you could be facing a full house or quads.
Next: The Turn - Bets now Double