Odds
Preflop > Pairs > Draws > Big hands/Bluffing > Other
Calculating the odds in poker is really pretty simple. You just need to figure out A: How many cards left in the deck will make your hand and B: How many cards there are left in the deck that you don't know about.
For example, let's say you have AK and the flop is 289. You want to figure out what the chances are of you hitting a pair on the turn. Since you have one ace and one king, and there are four of each in the deck, that means there are 3 kings and 3 aces left that may not have been dealt. That means you have 6 outs. And since you can see 5 cards you know there are 52 - 5 = 47 cards that you don't know about. To find out the odds of hitting your pair, divide your outs (6) by the number of unknown cards (47) and you'll get around 0.12766. To get a percentage, multiply that number by 100. That means the chance of hitting the pair on the turn is about 12.766%. Note that the number of cards dealt to other people doesn't matter at all since they are completely unknown.
Doing this calculation during an actual poker game would probably take too long, so there's a pretty well-known shortcut for calculating odds. Just multiply your outs by 2 and you'll get a percentage chance of hitting the hand on the next card (6 outs= 12% chance, etc). This method isn't perfect, but it's good enough.
Now that you know how to calculate your percentage chance of winning a hand, you can start to put these odds to use. The first way you do this is through pot odds. Pot odds is used mostly when deciding whether to call an all-in. Basically, it's a comparison of the amount of money you need to put in and the amount of money you stand to win, and then a comparison of this ratio to your chances of winning. Let's say, for example, that you have a draw to the nut flush on the flop. There's $500 in the pot, and the other person in the pot goes all-in for his last $400. At this point, you have to risk $400 to reel in a pot of $1300- a ratio of 4/13 or about 0.3. This means that you'll need at least a 30% chance to win for the call to be economical. So, let's figure out your odds. First off, there are 13 of each suit in a 52 card deck. Since there are 4 of your suit showing (2 have been dealt to you and two came on the flop) that means you have 9 outs. To get the percentage chance of hitting it on each additional card, multiply your outs by 2 to get 9x2= 18%. Since there are two cards to come, your chance of hitting the flush is roughly 36% (it's actually slightly less). Therefore, pot odds dictate that it is correct to call here.
The final type of odds in poker is implied odds. What calculating "implied odds" entails is basically guessing the future actions of your opponents. If you call a bet with a draw for example, you are usually counting on the possibility that your opponent will put more money in the pot if you hit your hand. Let's say you have an open ended straight draw on the turn. This has 8 outs, so the chance of hitting it on the river is about 16%. If your opponent bets $200 into a $500 pot, the ratio is 2/9- meaning you need a 22% chance to win to have correct pot odds. But, since theres a chance you can get more money into the pot if you hit your straight (and presumably have the best hand), it's still right to call here.
In a way, poker strategy is just one big exercise in figuring out the implied odds of any given situation. While breaking every situation down to its core odds would be tedious (and impossible), a basic knowledge and appreciation of them is crucial to a strong poker game plan.
