However, most of the time we want to see this in hand odds,
which will be explained after you read about pot odds. To change
a percent to odds, the formula is:
Odds = ( 1 / Percentage ) - 1
Thus, to change the 24% draw into an odd we can use, we do the
following:
Odds = ( 1 / 24% Two Overcard Draw ) - 1
= ( 1 / 0.24 ) - 1
= 4.17 - 1
= 3.17 or approx 3.2
ANALYZING PROBABILITIES IN DEPTH
You may want to skip this section and go back to it later. Some
of this is pretty deep. But important!
Getting a handle on the probability of being dealt various poker
hands is one of the most important and valuable skills a player can
have. We present a number of different ways to do these
calculations, from a rough guesstimate system called the 2-4 Rule
to the actual combination math.
The first odds calculation that must be made is to determine the
total number of possible poker hands in a deck.
As weve shown, a poker hand consists of 5 cards drawn from a
deck of 52 cards. Therefore, the number of combinations is
COMBIN(52, 5) = 2,598,960.
If you use Microsoft Excel, you can duplicate these calculations
using the COMBIN factor. COMBIN returns the number of
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combinations for a given number of items. To find the COMBIN
factor in Excel go to INSERT . . . FUNCTION . . . MATH & TRIG.
For each of the above ?Number of Combinations? we divide by
this number to get the probability of being dealt any particular
hand.
For the calculations, we will first split out the ?No Pair? hands
which include Royal
Straight Flushes,
Straight Flushes, Flushes,
Straights, and ?Nothings?. Then, we will look at all combinations
that have at least 1 pair.
The cards in a hand without any pairs will have 5 different
denominations selected randomly from the 13 available (2, 3,
4...Ace). Also, each of the 5 denominations will select 1 suit from
the four available suits. Thus the total number of no-pair hands
will equal:
COMBIN(13, 5) * (COMBIN(4, 1))^5 = 1287 * 1024 = 1,317,888.
A
Straight Flush is made up of 5 consecutive cards in the same suit
and may have a high card of 5, 6, 7, 8, 9, 10, Jack, Queen, King, or
Ace for a total of 10 different
Ranks. Each of these may be in any of
4 suits. Thus there are 40 possible
Straight Flushes. An Ace high
Straight Flush is a
Royal Flush. Since there are only 4 different
suits there are only 4 possible Royal
Straight Flushes. When we
subtract the 4 Royal
Straight Flushes from the total of 40 Straight
Flushes we are left with 36 other
Straight Flushes that are King
high or less.
A Flush consists of any 5 of the 13 cards from a particular suit.
There are 4 possible suits. The number of possible Flushes is:
COMBIN(13, 5) * 4 = 5,148. However, this includes the 40 possible
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Straight Flushes. When we subtract these out, we are left with:
5,148 - 40 = 5,108 possible ordinary flushes.
A straight consists of 5 cards with consecutive denominations and
may have a high card of 5, 6, 7, 8, 9, 10, Jack, Queen, King, or Ace
for a total of 10 different
Ranks. Each of these 5 cards may be in any
of the 4 suits. Thus there are 10 * 4^5 = 10,240 different possible
straights. However, this total includes the 40 possible Straight
Flushes. Thus we subtract 40, which leaves us with 10,200 possible
ordinary straights.
Finally, we come to the ?nothing? hands which are basically all the
left over garbage. This is simply the total number of ?No Pair?
hands minus all the good stuff. This gives us: 1,317,888 - 4 - 36 -
5,108 - 10,200 = 1,302,540 ?nothing? hands.
How about the odds of getting 1 pair or better?
A hand with just 1 pair has 4 different denominations selected
randomly from the 13 available denominations. 3 of these
denominations will select 1 card randomly from the 4 available
suits. The 4th denomination will select 2 cards from the available 4
suits. Finally, the pair can be any one of the four available
denominations. Thus the calculation is: COMBIN(13, 4) *
(COMBIN(4, 1))^3 * COMBIN( 4, 2) * 4 = 1,098,240 possible hands
that have just one pair.
The calculation for a hand with
Two Pairs is similar. We will have 3
random denominations taken from the 13 available. Two of these
denominations will use 2 of the four available suits while the third
denomination selects 1 of the four available suits. The
Singleton
card may be any one of the three denominations. Thus, the
calculation becomes: COMBIN(13, 3) * (COMBIN(4, 2))^2 *
COMBIN(4, 1) * 3 = 123,552 possible hands with 2 pairs.
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Three Of A Kind is calculated in a similar manner. There will be 3
different denominations from the 13 possible denominations. One
denomination will select 3 of the 4 available suits while the other
two denominations select 1 card from each of the 4 possible suits.
Finally, the
Three Of A Kind can be in any of the three
denominations. The calculation becomes: COMBIN(13, 3) *
COMBIN(4, 3) * (COMBIN(4, 1))^2 * 3 = 54,912 possible hands with
3 of a kind.
The next calculation will be for a
Full House. A
Full House only
uses 2 of the 13 denominations. One of these will select 3 cards
from the 4 available while the other selects 2 cards from the 4
available. Finally the denomination that has 3 cards can be either
one of the 2 denominations that we are using. This gives us:
COMBIN(13, 2) * COMBIN(4, 3) * COMBIN(4 , 2) * 2 = 3,744
possible
Full Houses.
The final calculation is for 4 of a kind. Again, we will select 2
denominations from the 13 available. One of these will select 4
cards from the 4 available (Obviously the only way to do this is to
take all four cards.) while the other denomination takes 1 of the
available 4 cards. The denomination that has 4 of a kind can be
either one of the 2 available denominations.
Thus, the calculation becomes: COMBIN(13, 2) * COMBIN( 4, 4) *
COMBIN( 4, 1) * 2 = 624 different ways of being dealt 4 of a kind.
Poker Odds From The Turn
Many players who really understand Hold'em odds still tend to
forget that the turn can change their odds dramatically. It's true
that for a flush draw, the card odds are 1.9 to 1 from the flop to the
river. However, this is a theoretical situation where it assumes
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there is no additional betting on the turn. Typically this is not
going to be the case so you will need to recalculate your card odds
and pot odds.
We will use the flush calculation example again and run through it
100 times assuming there was $20 in the pot on the flop with two
$5 bets. On the turn, this leaves $30 in the pot, plus a $10 bet from
your opponent to call.
Cost to Play = 100 hands * $10 to call on turn = -$1,000
Pot Value = $30 + $10 bet + $10 call
Odds to Win = 4.1:1 or 19% (From the turn)
Total Hands Won = 100 * Odds to Win (19%) = 19 wins
Net Profit = Net Cost to Play + (Total Times Won * Pot Value)
= -$1,000 + (19 * $50)
= -$1,000 + $900
= -$100 Profit
Now, you can see that what was a very profitable draw on the flop
suddenly turned into a not so great draw on the turn. This is
because by not hitting your flush by the turn, it lowered your
chances of making a flush by the river. The odds thus increased to
4.1 to 1 instead of 1.9 to 1. So even though the pot odds remained
the same at 4:1, because the card odds went down, this flush draw
has now become unprofitable.
Realizing the dynamic changes in your odds is extremely
important so that you don't go making incorrect draws based on
odds from the flop. Just remember that your odds essentially
double from the flop to the turn, so adjust your play accordingly.
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Each entry in the following table is the result of 1,000,000
simulated hands of Texas Hold 'em played to the showdown and
represents the percentage of pots won (including partial pots in
the case of splits) by the indicated hand against the indicated
number of opponents holding random hands.
The study shows a very clear correlation between your odds of
success against the number of players. Notice the JJ, TT, 99
anomaly where the power of these cards increase dramatically
over perceived better pocket cards - depending on how many
players are left. The hands indicated in BOLD can have impressive
results but require aggressive raising to force out weaker players.