All Poker Formulas

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Introduction

In this video I breakdown how to look at a poker hand using ranges and how that has developed over the years. I no longer only think about my hand vs.

Derivations for Five Card Stud

The game of poker is a card game played among two or more players for several rounds. There are several varieties of the game, but they all tend to have these aspects in common: The game begins with each player putting down money allocated for betting. During each round of play, players are dealt cards from a standard 52-card deck, and the goal of each player is to have the best 5-card hand at. The reason all of this is important to Texas holdem players is that you can use all of this math to help you win. Though there are thousands of possibilities on every hand of Texas holdem, you can use the fact that everything is based on a set of 52 cards to predict outcomes and possibilities at every stage for every hand.

The poker odds calculators on CardPlayer.com let you run any scenario that you see at the poker table, see your odds and outs, and cover the math of winning and losing poker hands. Texas Hold'em Omaha. No-Limit or “All In” poker gives each player the chance to only bet what’s in front of them at the poker table. These are called “table stakes,” it means that in a poker hand you can only bet whatever money or chips you had on the table when the hand started.

I have been asked so many times how I derived the probabilities of drawing each poker hand that I have created this section to explain the calculation. This assumes some level mathematical proficiency; anyone comfortable with high school math should be able to work through this explanation. The skills used here can be applied to a wide range of probability problems.

The Factorial Function

If you already know about the factorial function you can skip ahead. If you think 5! means to yell the number five then keep reading.

The instructions for your living room couch will probably recommend that you rearrange the cushions on a regular basis. Let's assume your couch has four cushions. How many combinations can you arrange them in? The answer is 4!, or 24. There are obviously 4 positions to put the first cushion, then there will be 3 positions left to put the second, 2 positions for the third, and only 1 for the last one, or 4*3*2*1 = 24. If you had n cushions there would be n*(n-1)*(n-2)* ... * 1 = n! ways to arrange them. Any scientific calculator should have a factorial button, usually denoted as x!, and the fact(x) function in Excel will give the factorial of x. The total number of ways to arrange 52 cards would be 52! = 8.065818 * 10⁶⁷.

The Combinatorial Function

Assume you want to form a committee of 4 people out of a pool of 10 people in your office. How many different combinations of people are there to choose from? The answer is 10!/(4!*(10-4)!) = 210. The general case is if you have to form a committee of y people out of a pool of x then there are x!/(y!*(x-y)!) combinations to choose from. Why? For the example given there would be 10! = 3,628,800 ways to put the 10 people in your office in order. You could consider the first four as the committee and the other six as the lucky ones. However you don't have to establish an order of the people in the committee or those who aren't in the committee. There are 4! = 24 ways to arrange the people in the committee and 6! = 720 ways to arrange the others. By dividing 10! by the product of 4! and 6! you will divide out the order of people in an out of the committee and be left with only the number of combinations, specifically (1*2*3*4*5*6*7*8*9*10)/((1*2*3*4)*(1*2*3*4*5*6)) = 210. The combin(x,y) function in Excel will tell you the number of ways you can arrange a group of y out of x.

Now we can determine the number of possible five card hands out of a 52 card deck. The answer is combin(52,5), or 52!/(5!*47!) = 2,598,960. If you're doing this by hand because your calculator doesn't have a factorial button and you don't have a copy of Excel, then realize that all the factors of 47! cancel out those in 52! leaving (52*51*50*49*48)/(1*2*3*4*5). The probability of forming any given hand is the number of ways it can be arranged divided by the total number of combinations of 2,598.960. Below are the number of combinations for each hand. Just divide by 2,598,960 to get the probability.

Poker Math

The next section shows how to derive the number of combinations of each poker hand in five card stud.

Royal Flush

There are four different ways to draw a royal flush (one for each suit).

Straight Flush

The highest card in a straight flush can be 5,6,7,8,9,10,Jack,Queen, or King. Thus there are 9 possible high cards, and 4 possible suits, creating 9 * 4 = 36 different possible straight flushes.

Four of a Kind

There are 13 different possible ranks of the 4 of a kind. The fifth card could be anything of the remaining 48. Thus there are 13 * 48 = 624 different four of a kinds.

Full House

There are 13 different possible ranks for the three of a kind, and 12 left for the two of a kind. There are 4 ways to arrange three cards of one rank (4 different cards to leave out), and combin(4,2) = 6 ways to arrange two cards of one rank. Thus there are 13 * 12 * 4 * 6 = 3,744 ways to create a full house.

Flush

There are 4 suits to choose from and combin(13,5) = 1,287 ways to arrange five cards in the same suit. From 1,287 subtract 10 for the ten high cards that can lead a straight, resulting in a straight flush, leaving 1,277. Then multiply for 4 for the four suits, resulting in 5,108 ways to form a flush.

Straight

The highest card in a straight can be 5,6,7,8,9,10,Jack,Queen,King, or Ace. Thus there are 10 possible high cards. Each card may be of four different suits. The number of ways to arrange five cards of four different suits is 4⁵ = 1024. Next subtract 4 from 1024 for the four ways to form a flush, resulting in a straight flush, leaving 1020. The total number of ways to form a straight is 10*1020=10,200.

Three of a Kind

There are 13 ranks to choose from for the three of a kind and 4 ways to arrange 3 cards among the four to choose from. There are combin(12,2) = 66 ways to arrange the other two ranks to choose from for the other two cards. In each of the two ranks there are four cards to choose from. Thus the number of ways to arrange a three of a kind is 13 * 4 * 66 * 4² = 54,912.

Two Pair

There are (13:2) = 78 ways to arrange the two ranks represented. In both ranks there are (4:2) = 6 ways to arrange two cards. There are 44 cards left for the fifth card. Thus there are 78 * 6² * 44 = 123,552 ways to arrange a two pair.

One Pair

There are 13 ranks to choose from for the pair and combin(4,2) = 6 ways to arrange the two cards in the pair. There are combin(12,3) = 220 ways to arrange the other three ranks of the singletons, and four cards to choose from in each rank. Thus there are 13 * 6 * 220 * 4³ = 1,098,240 ways to arrange a pair.

Nothing

First find the number of ways to choose five different ranks out of 13, which is combin(13,5) = 1287. Then subtract 10 for the 10 different high cards that can lead a straight, leaving you with 1277. Each card can be of 1 of 4 suits so there are 4⁵=1024 different ways to arrange the suits in each of the 1277 combinations. However we must subtract 4 from the 1024 for the four ways to form a flush, leaving 1020. So the final number of ways to arrange a high card hand is 1277*1020=1,302,540.

Specific High Card

For example, let's find the probability of drawing a jack-high. There must be four different cards in the hand all less than a jack, of which there are 9 to choose from. The number of ways to arrange 4 ranks out of 9 is combin(9,4) = 126. We must then subtract 1 for the 10-9-8-7 combination which would form a straight, leaving 125. From above we know there are 1020 ways to arrange the suits. Multiplying 125 by 1020 yields 127,500 which the number of ways to form a jack-high hand. For ace-high remember to subtract 2 rather than 1 from the total number of ways to arrange the ranks since A-K-Q-J-10 and 5-4-3-2-A are both valid straights. Here is a good site that also explains how to calculate poker probabilities.

Five Card Draw — High Card Hands

Hand	Combinations	Probability
Ace high	502,860	0.19341583
King high	335,580	0.12912088
Queen high	213,180	0.08202512
Jack high	127,500	0.04905808
10 high	70,380	0.02708006
9 high	34,680	0.01334380
8 high	14,280	0.00549451
7 high	4,080	0.00156986
Total	1,302,540	0.501177394

Ace/King High

For the benefit of those interested in Caribbean Stud Poker I will calculate the probability of drawing ace high with a second highest card of a king. The other three cards must all be different and range in rank from queen to two. The number of ways to arrange 3 out of 11 ranks is (11:3) = 165. Subtract one for Q-J-10, which would form a straight, and you are left with 164 combinations. As above there 1020 ways to arrange the suits and avoid a flush. The final number of ways to arrange ace/king is 164*1020=167,280.

Internal Links

For lots of other probabilities in poker, please see my section on Probabilities in Poker.

Written by:Michael Shackleford

The card game of poker has many variations, most of which were created in the United States in the mid-1900s. The standard order of play applies to most of these games, but to fully specify a poker game requires details about which hand values are used, the number of betting rounds, and exactly what cards are dealt and what other actions are taken between rounds.

Popular poker variants[edit]

The three most popular poker variants are spread in casinos and poker rooms worldwide and can be divided into the following groups:

Draw poker: Games in which players are dealt a complete hand, hidden, and then improve it by replacing cards. The most common of these is five-card draw.
Stud poker: Games in which each player receives a combination of face-up cards and face-down cards in multiple betting rounds. The most common of these are five-card stud and seven-card stud. These two variants are further played in other different formats.
Community card poker: Games in which each player's incomplete hidden hand is combined with shared face-up cards. The most common of these are Texas hold 'em and Omaha hold 'em.

Here are more common rule variations:

Lowball: The lowest hand wins the pot. There are different rules about whether or not aces count as low, and the effects of straights and flushes. The most common variants are Razz and 2-7 Triple Draw
High-low split: the highest and lowest hands split the pot. Generally there is a qualifier for the low hand. For example, the low hand must have 5 cards with ranks of 8 or less. In most high-low games the usual rank of poker hands is observed, so that an unsuited broken straight (7-5-4-3-2) wins low (see Morehead, Official Rules of Card Games). In a variant, based on Lowball, where only the low hand wins, a straight or a flush does not matter for a low hand. So the best low hand is 5-4-3-2-A, suited or not.
Players can pass cards to each other. An example of this would be Anaconda.
Kill game: When a fixed limit game is played and a player wins two pots in a row, the stakes are doubled. In some split-pot games, a player winning both halves of the pot may also cause a kill. In some variants of Lowball, a player may choose to kill by placing a double bet after seeing his first two cards.
Wild cards are added. This can range from simply making deuces wild to the 7-card stud variant named baseball.
A twist round in which players can buy another card from the deck. If a player does not like the purchased card, the player can purchase another one by adding money to the pot. This is sometimes called a 'tittle.'
A stripped deck may be used. Poker was first played with only 20 cards. In the spirit of poker history, players will sometimes only play with a stripped deck. A popular poker game in Spain is played with cards 8-A. It is played similar to hold'em, except that one card is dealt at a time and a player must use both hole cards.
Roll your own is played in stud games, and allows the player to determine which of his or her cards are turned up and visible to the other players. In a game like Seven-card Stud, the 'roll' action only applies to the first 3 cards, all of which are dealt face down. Each player then determines which card to expose. Play then continues as with regular Seven-card Stud. But a game like Mexican stud applies the roll option throughout the game. Two cards are dealt face down, and the players roll one card up. The game continues just as in Five-card Stud, except the cards are dealt face down, and each player then decides which of the two down cards is exposed.^[1]

Mixed poker games[edit]

Poker can be played in a mixed game format, for example one half-hour of Texas hold 'em followed by one half-hour of Seven-card stud. There are many types of mixed poker games. The most notable mixed poker variation is H.O.R.S.E. poker. H.O.R.S.E. is a mix of Texas hold 'em, Omaha high-low, Razz, Seven-card stud and Seven-card stud Eight-or-better. Each game will usually be played for a fixed number of hands or time and then the players will move on to the next game.

Other mixed games include:

H.O.S.E. – same as H.O.R.S.E., except without Razz.
H.O.E. – same as H.O.R.S.E, except no Razz or Seven-card stud.
H.O. – Texas hold 'em and Omaha high-low
O.E. – Omaha high-low and Seven-card Stud Eight or better.
H.A. – Pot limit Texas hold 'em and pot limit Omaha.
Omaha High-low Mixed – Fixed limit Omaha and pot limit Omaha high-low
Holdem Mixed – Fixed limit and no limit Texas hold 'em.
Eight Game Mix – Fixed limit 2-7 Triple Draw, fixed limit Texas hold 'em, fixed limit Omaha Hi-Low Eight or better, Razz, fixed limit Seven-card stud, fixed limit Seven-card stud Hi-Low eight or better, no limit Texas hold 'em and pot limit Omaha.
Ten Game Mix (introduced at 2011 World Series of Poker) – No limit Hold'em, fixed limit Seven-card Razz, fixed limit Hold'em, fixed limit Badugi, fixed limit Seven-card Stud, no limit 2-7 Single Draw, fixed limit Omaha Hi-Low eight or better, pot limit Omaha, fixed limit 2-7 Triple Draw and fixed limit Seven-card stud Hi-Low eight or better (played with 6 players on a table).

Specific poker variant games[edit]

Some poker games don't fit neatly into the above categories, and some have features of more than one of these categories. These variants are most often played in home games, usually as part of a dealer's choice format.

High Chicago or Low Chicago[edit]

Either of these two versions can be played in any stud high game. In High Chicago, or sometimes simply called Chicago, the player with the highest spade face down (referred to as in the hole) receives half the pot. In Low Chicago, the player with the lowest spade in the hole receives half of the pot, with the A♠ being the lowest. If the player with the highest hand also has the highest/lowest spade in the hole, then that player receives the entire pot - having won both sides of the bet.

Follow the Queen[edit]

This 7-card stud game uses a wild-card designated as whichever card is immediately dealt (exposed, or face-up) after any queen previously dealt (exposed). In the event that the final card dealt (exposed) is itself a queen, then all queens are wild. If no queens are dealt (exposed), then there are no wilds for that hand. Betting is the same as in normal 7-card stud games. Follow the Queen is a typical game variant in Dealer's Choice poker games.^[2]^[3]

Countdown[edit]

In this 5-card game, the dealer gives each player 5 cards face down. After the first round of betting, each player may choose to replace zero to three cards. A second round of betting follows and then players may opt to replace zero to two cards. Upon completing another round of betting, each player may replace one card of the cards in their hand. After a final round of betting, any remaining players show their hands, and the highest 5 card hand wins. The cost of cards doubles each round. For example, if the dealer says each replacement card costs $10 in the first round, then each card costs $20 in the second round, and $40 in the final round. When players purchase cards to replace ones in their hand, they put the cost of the cards in the pot.^[4]

This game will only work with 4 players (or fewer) otherwise you will run out of cards.

Billabong and Shanghai[edit]

Just as Oxford stud is a mixed stud/community card version of Texas hold 'em, Billabong is a mixed version of Manila. Each player is dealt two down-cards and one up-card. Low up-card starts the betting with a Bring-in if you are playing with one, otherwise high card starts the betting. Next, two community cards are dealt, followed by a second betting round, beginning with the player with the best exposed partial poker hand (counting the community cards, as in Oxford stud). Then a third community card is dealt, followed by a third betting round. Finally a fourth community card is dealt, followed by a fourth betting round and showdown. Each player plays the best five-card hand he can make from the three in his hand plus the four on the board in any combination.

Shanghai is the same game with an extra hole card, but no more than two hole cards play. That is, the game begins with each player being dealt three down-cards and one up-card; each player must discard one of his hole cards at some point during the game as determined ahead of time. The most common variation is to discard immediately as in Pineapple; the second most common is to discard just before showdown as in Tahoe.

Guts[edit]

Guts is a family of games that are cousins of poker rather than poker variants. They usually involve hands of 3 or fewer cards, ranked similarly to hands in poker, and multiple successive rounds of betting each of which consist of the decision to be 'in' or 'out', and each with its own showdown. The losers of rounds of guts generally match or double the pot, which grows rapidly.

Five-O poker[edit]

Five-O Poker is a heads-up poker variant in which both players must play five hands of five cards simultaneously. Four of the five cards in each hand are face-up. Once all five hands are down, there is a single round of betting. The winner is determined by matching each hand to the corresponding hand of the opponent. The player with the stronger poker hand in three (or more) out of the five columns, wins, unless a player folds on a bet that was made. If a player beats their opponent with all five hands, this is called a “Five-O” win.

Chinese poker[edit]

Chinese poker is a 2-4 player poker game with thirteen cards. The idea is to make three poker hands with increasing rank : two with five cards and one with three cards. If one of the hands does not adhere to increasing rank (i.e. is mis-set), the hand is declared dead and results in some sort of penalty.

Kuhn poker[edit]

Kuhn poker, using a three card deck, is more of game theory problem than an actual game people play, but it can be played by two players.^[5]

References[edit]

^Pagat.com: Roll Your Own
^Pokernews.com: Fun Home Poker Game Rules - Follow the Queen
^Pokerrules.net: How to Play Follow the Queen
^Pokerrules.net: How to Play Countdown Poker
^'A Parameterized Family of Equilibrium Profiles for Three-Player Kuhn Poker'(PDF).