Poker Odds Probabilities Rating: 5,9/10 3117 reviews
The probability of a straight flush or an ace low straight will be reduced in case they won’t be counted. They will become 9/10 as common as they usually would be. This pages will tell you more about card outs: Calculating Card Outs; Pot odds. In poker, pot odds are used to determine the expected value of a. The chances of getting a top starting hand (of double aces, picture pairs or A-K. Calculating Poker Odds for Dummies - A FREE, #1 guide to mastering odds. How to quickly count outs to judge the value & chance of winning a hand in 2021.
One of the games that have seen a flurry of interest over the last few months is Six Plus Hold’em, also referred to as Short Deck Poker.
Six Plus Hold’em is an exciting and fun poker variant based on Texas Hold’em where the game is played with a deck of 36 cards as opposed to the usual 52 cards in traditional hold’em. Deuces through fives are removed from the deck giving the game its name Six Plus Hold’em/6+ or Short Deck Poker.
Poker odds give you the probability of winning any given hand. Higher odds mean a lower chance of winning, meaning that when the odds are large against you it’ll be a long time until you succeed. Each of the 2,598,960 possible hands of poker is equally likely when dealt 5 cards from a standard poker deck. Because of this, one can use probability by outcomes to compute the probabilities of each classification of poker hand. The binomial coefficient can be used to.
Aces are played both low and high, making both a low-end straight A6789 and the high JQKTA. Also, with a shortened deck, the game changes a bit in terms of hand rankings and rules. A Flush beats a Full House and in most places where Six Plus is offered, a Set or a Three-of-a-Kind beats a Straight.
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Because the low cards are removed, there are more playable hands compared with traditional Hold’em, and so it is more of an action-orientated game. Not only are the hand rankings modified but so are the mathematics and odds/probabilities of the majority of hands.
Before we talk about the odds and probabilities of some of the hands, let’s have a look at the hand rankings offered in Six Plus Hold’em (ranked from the highest hand to the lowest):
Six Plus Hold’em Hand Rankings Comparison
| Traditional Hold’em | 6+ Plus Hold’em (Trips beat Straight) | 6+ Plus Hold’em (Straight beat Trips) |
|---|---|---|
| Royal Flush | Royal Flush | Royal Flush |
| Straight Flush | Straight Flush | Straight Flush |
| Four of a Kind | Four of a Kind | Four of a Kind |
| Full House | Flush | Flush |
| Flush | Full House | Full House |
| Straight | Three-of-a-Kind | Straight |
| Three-of-a-Kind | Straight | Three-of-a-Kind |
| Two Pair | Two Pair | Two Pair |
| One Pair | One Pair | One Pair |
| High Card | High Card | High Card |
One may wonder why a Flush is ranked higher than a Full House or why Three-of-a-Kind is ranked above a Straight. That’s because in Six Plus Hold’em, a Flush is harder to make since there are only nine cards in each suit instead of thirteen. Similarly, the stripped-deck also means that the remaining 36 cards are much closer in rank and so there will be smaller gaps between the cards in the hand and those on the board. This increases the probability of a hand becoming a Straight and hence Straights are ranked higher than a Three-of-a-Kind.
However, it is worth noting that the rules vary from game to game. For example, in the Short Deck variant offered in the Triton Poker Series, a Straight is ranked higher than a Three-of-a-Kind like in traditional hold’em even though mathematically a player would hit a Straight more.
One of the reasons why an operator would rank a Straight higher than Three-of-a-Kind is because it would generate more action. If Trips were ranked higher, a player with a Straight draw would have no reason to continue the hand as he or she would be drawing dead.
Let’s take a look at the odds/probabilities of hitting some of the hands:
Six Plus Hold’em vs Traditional Hold’em (Odds and Probabilities comparison)
| Traditional Hold’em | Six Plus Hold’em/Short Deck Poker | |
|---|---|---|
| Getting Dealt Aces | 1 in 221 (0.45%) | 1 in 105 (0.95%) |
| Aces Win % vs a Random Hand | 85% | 77% |
| Getting Dealt any Pocket Pair | 5.90% | 8.60% |
| Hitting a Set with a Pocket Pair | 11.80% | 18% |
| Hitting an Open-Ended Straight by the River | 31.50% | 48% |
| Possible Starting Hands | 1326 | 630 |
As you can see in the table above, the odds of being dealt pocket Aces are doubled as you now get the powerful starting hand dealt once in every 105 hands, as opposed to once in every 221 hands with a full 52-card deck. However, the probability of winning a hand with aces vs a random hand decreases from 85% in traditional hold’em to 77% in Six Plus Hold’em.
The probability of hitting a Set with pocket pairs increases to 18% from 11.8%, and the probability of hitting an open-ended Straight by the River also increases to 48% in 6+ Hold’em compared with 31.5% in traditional Hold’em.
Let’s now have a look at some of the pre-flop all-in hand situations:
Six Plus Hold’em vs Traditional Hold’em (Hands Comparison)
| Hand All-in Pre-Flop | Traditional Hold’em | 6+ Hold’em (Trips beat Straight) | 6+ Hold’em (Straight beat Trips) |
|---|---|---|---|
| Ac Ks vs Th Td | 43% vs 57% | 47% vs 53% | 49% vs 51% |
| Ac Ks vs Jc Th | 63% vs 37% | 53% vs 47% | 52% vs 48% |
| As Ah vs 6s 6h | 81% vs 19% | 76% vs 24% | 76% vs 24% |
As mentioned earlier, the equities run very close to each other with the shortened deck and so a hand like Ace-King versus Jack-Ten is almost a coin-flip, whereas the former is a favorite in Texas Hold’em. Again, a hand like Ace-King versus a pocket pair like Tens is a coin-flip in 6+, whereas a pocket pair is a slight favorite in normal Hold’em.
Now, let’s take a look at the probabilities when a connected or wet Flop is dealt:
Player 1: Ac Ks
Player 2: Td 9h
Flop: Kh 8c 7d
| Traditional Hold’em | 6+ Hold’em (Trips beat Straight) | 6+ Hold’em (Straight beat Trips) | |
|---|---|---|---|
| Player 1 vs Player 2 | 66% vs 34% | 52% vs 48% | 48% vs 52% |
In traditional Hold’em, Ace-King is a favorite with 66% and Player 2 is chasing the Straight draw with a close to 34% chance of hitting it. However, the probability significantly changes in both variants of 6+ Hold’em. In a variant where Trips beat a Straight, Player 1 is only a slight favorite with just 52% (more like a coin-flip). However, in a Short Deck game where a Straight beat Trips, Player 2 is now slightly favorite with 52% chance of hitting a Straight by the river.
Another hand:
Player 1: As Ah
Player 2: Qd Jh
Flop: Ad Th 9s
| Traditional Hold’em | 6+ Hold’em (Trips Beat a Straight) | 6+ Hold’em (Straight beat Trips) | |
|---|---|---|---|
| Player 1 vs Player 2 | 74% vs 26% | 100% vs 0% | 68% vs 32% |
It’s pretty clear when it comes to normal Hold’em, but in a Short Deck variant where Trips beat a Straight, Player 2 is drawing dead as opposed to the other variant where Player 2 still has a 32% of chance of completing a Straight by the River.
This post works with 5-card Poker hands drawn from a standard deck of 52 cards. The discussion is mostly mathematical, using the Poker hands to illustrate counting techniques and calculation of probabilities
Working with poker hands is an excellent way to illustrate the counting techniques covered previously in this blog – multiplication principle, permutation and combination (also covered here). There are 2,598,960 many possible 5-card Poker hands. Thus the probability of obtaining any one specific hand is 1 in 2,598,960 (roughly 1 in 2.6 million). The probability of obtaining a given type of hands (e.g. three of a kind) is the number of possible hands for that type over 2,598,960. Thus this is primarily a counting exercise.
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Preliminary Calculation
Usually the order in which the cards are dealt is not important (except in the case of stud poker). Thus the following three examples point to the same poker hand. The only difference is the order in which the cards are dealt.
Poker Odds Chart
These are the same hand. Order is not important.
The number of possible 5-card poker hands would then be the same as the number of 5-element subsets of 52 objects. The following is the total number of 5-card poker hands drawn from a standard deck of 52 cards.
The notation is called the binomial coefficient and is pronounced “n choose r”, which is identical to the number of -element subsets of a set with objects. Other notations for are , and . Many calculators have a function for . Of course the calculation can also be done by definition by first calculating factorials.
Thus the probability of obtaining a specific hand (say, 2, 6, 10, K, A, all diamond) would be 1 in 2,598,960. If 5 cards are randomly drawn, what is the probability of getting a 5-card hand consisting of all diamond cards? It is
This is definitely a very rare event (less than 0.05% chance of happening). The numerator 1,287 is the number of hands consisting of all diamond cards, which is obtained by the following calculation.
The reasoning for the above calculation is that to draw a 5-card hand consisting of all diamond, we are drawing 5 cards from the 13 diamond cards and drawing zero cards from the other 39 cards. Since (there is only one way to draw nothing), is the number of hands with all diamonds.
If 5 cards are randomly drawn, what is the probability of getting a 5-card hand consisting of cards in one suit? The probability of getting all 5 cards in another suit (say heart) would also be 1287/2598960. So we have the following derivation.
Thus getting a hand with all cards in one suit is 4 times more likely than getting one with all diamond, but is still a rare event (with about a 0.2% chance of happening). Some of the higher ranked poker hands are in one suit but with additional strict requirements. They will be further discussed below.
Another example. What is the probability of obtaining a hand that has 3 diamonds and 2 hearts? The answer is 22308/2598960 = 0.008583433. The number of “3 diamond, 2 heart” hands is calculated as follows:
One theme that emerges is that the multiplication principle is behind the numerator of a poker hand probability. For example, we can think of the process to get a 5-card hand with 3 diamonds and 2 hearts in three steps. The first is to draw 3 cards from the 13 diamond cards, the second is to draw 2 cards from the 13 heart cards, and the third is to draw zero from the remaining 26 cards. The third step can be omitted since the number of ways of choosing zero is 1. In any case, the number of possible ways to carry out that 2-step (or 3-step) process is to multiply all the possibilities together.
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The Poker Hands
Here’s a ranking chart of the Poker hands.
The chart lists the rankings with an example for each ranking. The examples are a good reminder of the definitions. The highest ranking of them all is the royal flush, which consists of 5 consecutive cards in one suit with the highest card being Ace. There is only one such hand in each suit. Thus the chance for getting a royal flush is 4 in 2,598,960.
Royal flush is a specific example of a straight flush, which consists of 5 consecutive cards in one suit. There are 10 such hands in one suit. So there are 40 hands for straight flush in total. A flush is a hand with 5 cards in the same suit but not in consecutive order (or not in sequence). Thus the requirement for flush is considerably more relaxed than a straight flush. A straight is like a straight flush in that the 5 cards are in sequence but the 5 cards in a straight are not of the same suit. For a more in depth discussion on Poker hands, see the Wikipedia entry on Poker hands.
The counting for some of these hands is done in the next section. The definition of the hands can be inferred from the above chart. For the sake of completeness, the following table lists out the definition.
Definitions of Poker Hands
| Poker Hand | Definition | |
|---|---|---|
| 1 | Royal Flush | A, K, Q, J, 10, all in the same suit |
| 2 | Straight Flush | Five consecutive cards, |
| all in the same suit | ||
| 3 | Four of a Kind | Four cards of the same rank, |
| one card of another rank | ||
| 4 | Full House | Three of a kind with a pair |
| 5 | Flush | Five cards of the same suit, |
| not in consecutive order | ||
| 6 | Straight | Five consecutive cards, |
| not of the same suit | ||
| 7 | Three of a Kind | Three cards of the same rank, |
| 2 cards of two other ranks | ||
| 8 | Two Pair | Two cards of the same rank, |
| two cards of another rank, | ||
| one card of a third rank | ||
| 9 | One Pair | Three cards of the same rank, |
| 3 cards of three other ranks | ||
| 10 | High Card | If no one has any of the above hands, |
| the player with the highest card wins |
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Counting Poker Hands
Straight Flush
Counting from A-K-Q-J-10, K-Q-J-10-9, Q-J-10-9-8, …, 6-5-4-3-2 to 5-4-3-2-A, there are 10 hands that are in sequence in a given suit. So there are 40 straight flush hands all together.
Four of a Kind
There is only one way to have a four of a kind for a given rank. The fifth card can be any one of the remaining 48 cards. Thus there are 48 possibilities of a four of a kind in one rank. Thus there are 13 x 48 = 624 many four of a kind in total.
Full House
Let’s fix two ranks, say 2 and 8. How many ways can we have three of 2 and two of 8? We are choosing 3 cards out of the four 2’s and choosing 2 cards out of the four 8’s. That would be = 4 x 6 = 24. But the two ranks can be other ranks too. How many ways can we pick two ranks out of 13? That would be 13 x 12 = 156. So the total number of possibilities for Full House is
Note that the multiplication principle is at work here. When we pick two ranks, the number of ways is 13 x 12 = 156. Why did we not use = 78?
Flush
There are = 1,287 possible hands with all cards in the same suit. Recall that there are only 10 straight flush on a given suit. Thus of all the 5-card hands with all cards in a given suit, there are 1,287-10 = 1,277 hands that are not straight flush. Thus the total number of flush hands is 4 x 1277 = 5,108.
Straight
There are 10 five-consecutive sequences in 13 cards (as shown in the explanation for straight flush in this section). In each such sequence, there are 4 choices for each card (one for each suit). Thus the number of 5-card hands with 5 cards in sequence is . Then we need to subtract the number of straight flushes (40) from this number. Thus the number of straight is 10240 – 10 = 10,200.
Three of a Kind
There are 13 ranks (from A, K, …, to 2). We choose one of them to have 3 cards in that rank and two other ranks to have one card in each of those ranks. The following derivation reflects all the choosing in this process.
Two Pair and One Pair
These two are left as exercises.
High Card
The count is the complement that makes up 2,598,960.
The following table gives the counts of all the poker hands. The probability is the fraction of the 2,598,960 hands that meet the requirement of the type of hands in question. Note that royal flush is not listed. This is because it is included in the count for straight flush. Royal flush is omitted so that he counts add up to 2,598,960.
Probabilities of Poker Hands
| Poker Hand | Count | Probability | |
|---|---|---|---|
| 2 | Straight Flush | 40 | 0.0000154 |
| 3 | Four of a Kind | 624 | 0.0002401 |
| 4 | Full House | 3,744 | 0.0014406 |
| 5 | Flush | 5,108 | 0.0019654 |
| 6 | Straight | 10,200 | 0.0039246 |
| 7 | Three of a Kind | 54,912 | 0.0211285 |
| 8 | Two Pair | 123,552 | 0.0475390 |
| 9 | One Pair | 1,098,240 | 0.4225690 |
| 10 | High Card | 1,302,540 | 0.5011774 |
| Total | 2,598,960 | 1.0000000 |
Poker And Probability
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2017 – Dan Ma
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