Odds Getting Blackjack 6 Deck Shoe

If the probability of a blackjack is p then the probability of not getting any blackjacks in 10 hands is 1- (1-p) 10. For example in a six deck game the answer would be 1- 0.952511 10 = 0.385251. What are the odds of getting 3 blackjacks in a row with 1 deck 4 players.

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Introduction

To use the basic strategy, look up your hand along the left vertical edge and the dealer's up card along the top. In both cases an A stands for ace. From top to bottom are the hard totals, soft totals, and splittable hands. There are two charts depending on whether the dealer hits or stands on soft 17.

Other basic strategy rules.

  • Never take insurance or 'even money.'
  • If there is no row for splitting (fives and tens), then look up your hand as a hard total (10 or 20).
  • If you can't split because of a limit on re-splitting, then look up your hand as a hard total.
6 deck blackjack odds

Ideally, the basic strategy shows the play which, on average, will result in the greatest win or the least loss per initial hand played. The way I usually go about this is to look at the initial 2-card hands only. Generally, this will result in the overall best play. However, soft 18 against a dealer ace when the dealer stands on soft 17 provides the only known exception that I am aware of for any number of decks. As my blackjack appendix 9 shows, a 2-card soft 18 vs A has an expected value of hitting of -0.100359, and of standing -0.100502. So with two cards it is very slightly better to hit. However, not all soft 18's are composed of two cards. The more the cards in the player's hand the more the odds favor standing. Simulations show that if forced to always hit or always stand, it is better to stand. I would like to thank Don Schlesinger for bringing this unusual play to my attention.

jlechuga928
does anyone know the answer?
Romes
Here's a FAQ from the Wizards Probability Page on WOO:
'What percentage of hands are suited blackjacks? Six-deck shoe, any suit.
RWR FROM TUSCON, USA
The probability of a suited blackjack in a six-deck game is 2*(4/13)*(6/311) = 0.0118723.'
So for 5 decks (not that it will change, but just do the math): 2*(4/13)*(5/259) = .0118, or 1.18%, all the same.
Be sure to leverage the search functionality, or even Google (all I did was type 'odds of getting suited blackjack' and the Wizards page was the first hit).
studmuffn
To add to Romes response, the probability of a suited blackjack, any suit, on any given hand (6-deck shoe) is about 1.18%. Therefore, the probability of not getting one is (1-.0118)= 98.82% for one hand. For your question, the probability of you not getting a suited blackjack in 100 hands is 0.9882^100= 0.3051. Therefore, your probability of getting at least one suited blackjack in 100 hands is
1-0.3051= 69.49%
This is for 100 repeated trials of taking cards out of a fresh shoe. I'm not sure what is meant by '5 deck shuffler', but if cards are discarded each hand, that will change your probability. That calculation would be rather cumbersome without programming.
Dieter
About 1 in 21 hands will be a blackjack.
About 1 in 4 of those will be suited.
This rough math gets you to 1/84=0.0119 chance of a suited blackjack, which is very close with much less math.
Romes

... which is very close with much less math.


Dieter, we're supposed to teach the kids that math is fun! =P
Playing it correctly means you've already won.
Dieter

Dieter, we're supposed to teach the kids that math is fun! =P


It is! Math is great fun!
... but useful approximations are at least as fun, and quite useful, and often easier to remember.
Every schoolkid should know that (about) 1 hand in 21 should be a blackjack. If you play, that's just something you should

6 Deck Blackjack Odds

know. It should be obvious that 1 in 4 will be suited.
As for accuracy... 1.187% vs 1.190% is darn close. 3 one thousandths of one percent close. Surely good enough for government work.
It's right up there with 'pi seconds is about a nanocentury'. (Of course, it's actually closer to 'square root of 10 seconds', but that's less fun.)
Card
May the cards fall in your favor.
Venthus

I'm not sure what is meant by '5 deck shuffler', but if cards are discarded each hand, that will change your probability. That calculation would be rather cumbersome without programming.


Based on how the question is phrased, I'd assume that the game is being played out of a 5-deck CSM. If you're not acquainted with them, they're pretty common machines in the US where the cards are fed back into the machine and reshuffled every few hands. Based on what I've seen, I'd estimate that, on average, ten cards will be in the discard at a given time. (Obviously, highly dependent on casino policy, number of hands, etc.)
It's close enough to playing with a constantly fresh n-deck game that the math shouldn't be thrown off by much though.
wudged

It is! Math is great fun!
... but useful approximations are at least as fun, and quite useful, and often easier to remember.
Every schoolkid should know that (about) 1 hand in 21 should be a blackjack. If you play, that's just something you should know. It should be obvious that 1 in 4 will be suited.
As for accuracy... 1.187% vs 1.190% is darn close. 3 one thousandths of one percent close. Surely good enough for government work.
It's right up there with 'pi seconds is about a nanocentury'. (Of course, it's actually closer to 'square root of 10 seconds', but that's less fun.)


Am I missing pi ~ 22/7 in that image? How could Randall forget that, or is it too obvious?

Blackjack Shoes 6 Deck

Dieter

Am I missing pi ~ 22/7 in that image? How could Randall forget that, or is it too obvious?


355/113 is closer. 7 digits of accuracy in only 6 digits.
Or, 4*atan(1) (in radians).
May the cards fall in your favor.
wudged

355/113 is closer. 7 digits of accuracy in only 6 digits.
Or, 4*atan(1) (in radians).


I agree 355/113 isbetter. 22/7 is just what we were told in some really basic math classes to use as an estimation.
4atan(1) = pi, not an approximation

6 Deck Blackjack Rules

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