How Many Decks Is Blackjack Played With
I’m getting more questions from blackjack players about continuous shufflers now that they are being used in more casinos. What players want to know is if the odds are better or worse withHenry Tamburin is the editor and publisher of the Blackjack Insider Newsletter and author of the best-selling Blackjack: Take the Money & Run. He is also the lead Instructor for the Golden Touch Blackjack course, a feature writer for Casino Player magazine (and 6 other publications); an owner of a casino gambling publishing company (www.rsucasinobooks.com) and the host of www.smartgaming.com. For a free three month subscription to the Henry's Blackjack Insider Newsletter with full membership privileges go to www.bjinsider.com/free. Henry's website is www.smartgaming.com
ShuffleMaster is a leader in production of continuous card shufflers like the one pictured here. a continuous shuffling machine (CSM).
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First, let’s make sure you understand what a CSM is because players often confuse them with automatic shufflers. The latter have been around a long time in casinos.
Fewer Decks = More Blackjacks. The main reason we say that fewer decks is better for players is that, in each deck, exactly 1/13 th of all cards are Aces. Yes, my friend was right, the initial proportions of card values to one another is equal no matter how many decks you play with. But step into any casino, you will find at least five to eight decks of cards used in Blackjack game! Excluding jokers, each of these decks come with a standard 52 cards. That being said, let’s take a look at how the decks of cards used in Blackjack affects the house edge as well as card counting.
Usually a casino will use two sets of multiple decks of cards on a blackjack table.
While one set of cards are used to play the game the other set is being shuffled offline by the automatic shuffler. When the cut card appears, the round is completed and then the dealer will swap the cards-the just used multi-decks will be placed in the automatic shuffler to be shuffled while the shuffled decks that were in the machine are put into play. The purpose of the automatic shuffler is to eliminate the wasted time involved in having the dealer manually shuffle the cards (from the casinos perspective, time is money, so their hourly profit goes up when they eliminate the wasted time in manually shuffling the cards).
The odds against the player in blackjack do not change when an automatic shuffler is used on the table to shuffle the multi-decks of cards. If the casino were using 6 decks of cards, they will usually deal 4.0-4.5 decks and then place the entire 6-decks into the automatic shuffler for shuffling while continue to play with the second set of freshly shuffled 6-decks of cards. With an automatic shuffler, about 70-75% of the cards are dealt out before the cards are reshuffled. This is an important point to remember.
The CSM was invented primarily to discourage card counting at blackjack. But it also has a negative effect over average players as you will soon see.
A CSM is a combination automatic shuffler and dealing shoe. Casinos usually place 5 decks of cards into the CSM. After a betting round is completed, the dealer will scoop up the just played cards (discards) and instead of placing them into a discard tray will insert the cards back into the CSM for shuffling with the remaining 4.5 or so decks of cards. (Some casinos will place the discards from several rounds into a small discard tray and then scoop up the deck or so of discards and place them back into the CSM).
Do you understand the difference between a CSM and automatic shuffler? With the latter most of the cards are played (ca. 70%) before the discards and unplayed cards are reshuffled. With a CSM, the discards are immediately returned to the shuffler to be randomly mixed with the unplayed card. . It’s possible that a specific card from the round just played might wind up being dealt in the next round.
So do the odds change when a CSM is used? The answer is yes, they change very slightly in favor of the player with the house edge against a basic strategy player in a typical 6-deck game reduced by about 0.1%.
The reason the CSM causes the house edge to go down ever so slightly is because of a phenomena known as the “cut card effect” (this increases the probability slightly of getting tens and blackjack when a CSM is used).
Now before you rush out and play blackjack on a table that uses a CSM, listen to the rest of the story. Even though the house edge goes down slightly with a CSM, this is more than negated by the increased speed of the game. Remember with a CSM dealt game there is never any down for shuffling cards. So on average the casino can deal about an extra round or two per hour resulting in about 20% more hands played per hour with a CSM and because they have the edge against the vast majority of players who play blackjack their hourly revenue goes up by 20%. From the player’s perspective, you will lose 20% faster on average playing against a CSM dealt game compared to a game dealt manually or with an automatic shuffler.
Casinos love to spin the tale that the reason they use a CSM is to foil card counters.
Yet you will rarely see a CSM used at high limit tables where most of the pro card counters would play. The reason is that most high rollers who know nothing of card counting are suspicious of the CSM and they insist that blackjack should be played the old fashion way or they will take their business elsewhere.
So in most casinos you will find CSM’s on the main casino floor where the table minimums are lower. It’s here on the $5 and $10 tables where the casino grinds out it’s 20% more revenue per hour against average low stakes players.
Casinos also like CSM’s because it allows them to always have the edge just like they enjoy with all their games. By using a CSM, blackjack becomes virtually unbeatable much like roulette, baccarat, Three Card Poker and other table games.
CSM’s are not cheap. Casinos coast to coast have been testing them for the past several years. In some casinos the devices were removed because of player complaints or because the extra revenue didn’t justify the extra cost of these devices. Nevertheless, casinos keep putting CSM on their tables in the hopes that the playing public will get accustomed to them.
My advice is to stay away from any blackjack table that uses a CSM. If more players do this casinos will reluctantly have to remove the machines and return to the more player friendly automatic shufflers (or manual shuffles). Blackjack is tough enough to beat without introducing devices that cause average player’s to lose more quickly.
Editor's Note: One of the most famous casino sites in Turkey named Turkcecasino25.com offers live blackjack. You can click and start playing online blackjack. You won't get a better shuffle, but it's a quick way to get some blackjack action.
- Appendices
- Miscellaneous
- External Links
Introduction
In playing blackjack online one problem I often face is not knowing how many decks are being used. This is a particular problem with Real Time Gaming casinos. The help files often do not indicate this rule, as well as other rules, and customer support are notorious for giving incorrect information on their own rules. So I devised a test to help determine the number of decks. This test is based on the player's first two cards and the dealer's first two.
The following table shows the probability for various configurations of the initial four cards in blackjack. Note the probabilites for a suited pair. Of all the hands I feel this is the best to test for, given both it's frequency and correlation to number of decks.
How Many Decks Is Blackjack Played With Poker
| 4-Card Hand | 1 deck | 2 decks | 4 decks | 6 decks | 8 decks |
|---|---|---|---|---|---|
| 4 singletons | 0.676110 | 0.63692 | 0.618504 | 0.612530 | 0.609573 |
| Non-suited pair | 0.304250 | 0.286614 | 0.278327 | 0.275638 | 0.274308 |
| Suited pair | 0.047769 | 0.069582 | 0.076566 | 0.080006 | |
| Two non-suited pairs | 0.010372 | 0.009771 | 0.009488 | 0.009397 | 0.009351 |
| Two suited pairs | 0.000271 | 0.000593 | 0.000725 | 0.000796 | |
| Two pair - 1 suited | 0.003257 | 0.004744 | 0.00522 | 0.005455 | |
| 3 of a kind - 3 suits | 0.009220 | 0.008685 | 0.008434 | 0.008353 | 0.008312 |
| 3 of a kind - 2 suits | 0.006514 | 0.009488 | 0.010441 | 0.010910 | |
| 3 of a kind - 1 suit | 0.000527 | 0.000773 | 0.000909 | ||
| 4 of a kind - 4 suits | 0.000048 | 0.000045 | 0.000044 | 0.000044 | 0.000043 |
| 4 of a kind - 2 suits (3&1) | 0.000033 | 0.000048 | 0.000057 | ||
| 4 of a kind - 2 suits (2&2) | 0.000017 | 0.000037 | 0.000045 | 0.000050 | |
| 4 of a kind - 3 suits | 0.000136 | 0.000198 | 0.000218 | 0.000227 | |
| 4 of a kind - 1 suit | 0.000001 | 0.000002 | 0.000003 | ||
| Total | 1 | 1 | 1 | 1 | 1 |
To determine the number of decks in an online blackjack game keep a tally of both the total number of hands played and the number of suited pairs. Only count a hands as a suited pair if the other two are singletons. For example one suited pair and one non-suited pair does not count. In a single deck game the ratio of suited pairs to total hands will obviously be zero. In double deck this ratio will be about 4.8%. In a 4-deck game the ratio increases to 7.0%. After that the differences are too subtle are to tell without a gigantic sample.
Of course if you ever notice three of the same card on the screen at once that rules out a double deck game immediately. Despite my lack of faith in customer support knowing their own rules I would suggest at least asking. If they give you an incorrect answer, and you can prove it, you may get some free money in your account as a way of thanks. This has happened to me several times.
Counting Cards Single Deck Blackjack
Unfortunately it takes a fairly large sample size to have confidence in the number of decks between 2 and 4. After 250 hands the probability that the sample mean in a 2-deck game will be greater than 6.96% (the 4-deck theoretical mean) is 5.29%. Likewise the probability that the sample mean in a 4-deck game will be less than 4.78% (the 2-deck theoretical mean) is 8.76%. Increasing the sample size to 500 these numbers become 1.11% and 2.76%. At 1000 the numbers are 0.06% and 0.34%.