Blackjack (also known as 21) is one of the most popular casino card games in the world. Much of blackjack's popularity is due to the mix of chance with elements of skill, and the publicity that surrounds card counting (keeping track of which cards have been played since the last shuffle). Blackjack's precursor was vingt-et-un ("twenty-one"), which originated in French casinos around 1700, and did not offer the 3:2 bonus for a two-card 21.

When 21 was first introduced in the United States it was not very popular, so gambling houses tried offering various bonus payouts to get the players to the tables. One such bonus was a 10-to-1 payout if the player's hand consisted of the ace of spades and a black Jack (either the Jack of clubs or the Jack of spades). This hand was called a "blackjack" and the name stuck to the game even though the bonus payout was soon abolished. As the game is currently played, a "blackjack" may not necessarily contain a jack or any black cards at all.

The hand with the highest total wins as long as it doesn't exceed 21; a hand with a higher total than 21 is said to bust or have too many. Cards 2 through 10 are worth their face value, and face cards (jack, queen, king) are also worth 10. An ace's value is 11 unless this would cause the player to bust, in which case it is worth 1. A hand in which an ace's value is counted as 11 is called a soft hand, because it cannot be busted if the player draws another card.

Each player's goal is to beat the dealer by having the higher, unbusted hand. Note that if the player busts he loses, even if the dealer also busts. If both the player and the dealer have the same point value, it is called a "push", and neither player nor dealer wins the hand. Each player has an independent game with the dealer, so it is possible for the dealer to lose to one player but still beat the other players in the same round.

The minimum bet is printed on a sign on the table and varies from casino to casino and table to table. After initial bets are placed, the dealer deals the cards, either from one or two hand-held decks of cards, known as a "pitch" game, or more commonly from a shoe containing four or more decks. The dealer gives two cards to each player including himself. One of the dealer's two cards is face-up so all the players can see it, and the other is face down. (The face-down card is known as the "hole card". In European blackjack, the hole card is not actually dealt until the players all play their hands.) The cards are dealt face up from a shoe, or face down if it is a pitch game.

In American blackjack, if the dealer's face-up card is an ace or a ten-value, the dealer checks his hole card to see if he has blackjack. This check occurs before any of the players play, but after they have been offered insurance (if the face-up card is an ace). If the dealer has blackjack, all players lose their initial bets, except players who also have blackjack, who push. (In some American casinos, the dealer does not actually check the hole card until after the players have all played. At that time, if the dealer turns out to have blackjack, all players who did not have blackjack lose their bets, and players who increased their bets by doubling or splitting lose only the original bet, and have the additional bets returned to them; thus, the end result is precisely as if the dealer had checked the hole card before playing.)

A two-card hand of 21 (an ace plus a ten-value card) is called a "blackjack" or a "natural", and is an automatic winner (unless the dealer has blackjack as well, in which case the hand is a push). A player with a natural is usually paid 3:2 on his bet. Some casinos pay only 6:5 on blackjacks; although this reduced payout has generally been restricted to single-deck games (Currrent Blackjack News, Pi Yee Press).^{[citation needed]} This reduced payout for a natural increases the house advantage over a player by as much as 1000 percent. The move was decried by longtime blackjack players^[1].

The player's options for playing his or her hand are:

• Hit: Take another card.
• Stand: Take no more cards.
• Double down: Double the wager, take exactly one more card, and then stand.
• Split: Double the wager and have each card be the first card in a new hand. This option is available only when both cards have the same value.
• Surrender: Forfeit half the bet and give up the hand. Surrender was common during the early- and mid-20th century, but is no longer offered at most casinos.

The player's turn is over after deciding to stand, doubling down to take a single card, or busting. If the player busts, he or she loses the bet even if the dealer goes on to bust.

After all the players have finished making their decisions, the dealer then reveals his or her hidden hole card and plays the hand. House rules say that the dealer must hit until he or she has at least 17, regardless of what the players have. In some casinos a dealer must also hit a soft 17 (a combination of cards adding up to either 7 or 17, such as an ace and a 6).

If the dealer busts then all remaining players win. Bets are normally paid out at the odds of 1:1. Players who push (tie) with the dealer receive their original bet back.

Some common rules variations include:

• Only one card for split Aces: a single new card is added to each Ace and the turn ends. They are thus regarded as 11-point cards. No other denomination is subject to this process.
• Multiple splits: If a player splits 2 cards and receives a third card of identical value, the hand can be split again, resulting in 3 hands. However, some casinos only allow a single split of the first 2 cards.
• Early surrender: Player has the option to surrender before dealer checks for Blackjack.
• Late surrender: Player has the option to surrender after dealer checks for Blackjack.
• Double-down restrictions: Double-down may only be allowed on certain combinations of cards (usually totaling 9, 10 or 11).
• Double-down after split: Double-down may not be allowed after splitting cards. The split hands are played normally otherwise.
• Split any tens: Players may split any 2 cards which are both worth 10 points, such as a Jack and Queen. This rule is rarely used, since 20 is a very strong hand which is unlikely to be split.
• European No-Hole-Card Rule: the dealer receives only one card, dealt face-up, and does not receive a second card (and thus does not check for blackjack) until players have acted. This means players lose not only their original bet, but also any additional money invested from splitting and doubling down. A game that has no-hole-card doesn't necessarily mean the player will lose additional bets as well as original bets. In some Australian casinos for example, a player beaten by a dealer blackjack may keep all split and double bets and lose only the original bet, thus the game plays the same as it would if there were a hole card.

Each blackjack variation has its own set of rules, strategies and odds. It is advised to take a look at the rules of the specific variation before playing. Many countries have legal acts and laws, which determine how a casino game of Blackjack must be played. Over 100 variations exist.^[2]

Insurance

If the dealer's upcard is an Ace, the player is offered the option of taking Insurance before the dealer checks his 'hole card'.

The player who wishes to take Insurance can bet an amount up to half his original bet. The Insurance bet is placed separately on a special portion of the table, which usually carries the words "Insurance Pays 2:1". The player who is taking Insurance is betting that the dealer was dealt a natural, i.e. a two-card 21 (a blackjack), and this bet by the player pays off 2:1 if it wins. It is called insurance since if the dealer has a blackjack, the bet wins the same amount of the player's Blackjack wager, such that if insurance is taken and the player doesn't have blackjack but dealer does, no money is lost. Of course the dealer can end up not having blackjack and the player can still win or lose the blackjack bet.

Insurance is a bad bet for the non-counting player who has no knowledge of the hole card because it has a house edge of 2 to 15%, depending on number of decks used and visible 10-cards ^[3]. Essentially, taking insurance amounts to betting that the dealer's hole card is a ten or face card. Since in an infinite deck, 4/13 of the cards are tens or face cards, an unbiased insurance wager would actually pay 9:4, or 2.25:1; since the bet only pays 2:1, the house has a strong advantage. However, if the player has been counting cards, he may know that more than a third of the deck is ten-value cards, in which case insurance becomes a good bet.

If a player has a natural (an ace and a ten or face-card) and the dealer is showing an ace, the dealer usually asks the player "Even money?" instead of offering insurance. If the player accepts the offer, he is immediately paid 1:1 for his natural, regardless of whether the dealer has blackjack. Thus, accepting "even money" has exactly the same payout as buying insurance: if the dealer does not have blackjack, the player would forfeit the insurance bet and win 3:2 on the natural, thus receiving a net payout equal to the original bet; if the dealer does have blackjack, the player would push on the natural and win 2:1 on the insurance wager, again receiving a net payout equal to the original bet. Since taking "even money" is equivalent to buying insurance, it is likewise a bad choice for the player, unless he has been counting cards and knows the deck has an unusually high proportion of ten-value cards.

In casinos where a hole card is dealt, a dealer who is showing a card with a value of Ace or 10 may slide the corner of his or her facedown card over a small mirror or electronic sensor on the tabletop in order to check whether he has a natural. This practice minimizes the risk of inadvertently revealing the hole card, which would give the sharp-eyed player a considerable advantage.

Basic strategy

Because blackjack has an element of player choice, players can reduce casino advantage to less than 1% by playing optimally. The complete set of optimal plays is known as basic strategy. There are slight variations depending on the house rules and number of decks.

The above is a basic strategy table for 3 or more decks, dealer stands on soft 17, double on any 2 cards, double after split allowed, dealer peeks for blackjack, and blackjack pays 3:2. Key:

S = Stand

H = Hit

Dh = Double (if not allowed then hit)

Ds = Double (if not allowed then stand)

SP = Split

SU = Surrender (if not allowed, then hit)

Most Las Vegas strip casinos hit on soft 17. This rule change requires a slightly modified basic strategy table -- double on 11 vs A, double on A/7 vs 2, and double on A/8 vs 6. Most casinos outside of Vegas still stand on soft 17.^{[citation needed]}

Card counting

Basic strategy provides the player with the optimal play for any blackjack situation based on millions of hands played in the long run. However in the short run, as the cards are dealt from the deck, the remaining deck is no longer complete. By keeping track of the cards that have already been played, it is possible to know when the cards remaining in the deck are advantageous for the player.

Card counting creates two opportunities:

• The player can make larger bets when he or she has the advantage. For example, the player can increase the starting bet if there are many aces and tens left in the deck, in the hope of hitting a blackjack.
• The player can use information about the remaining cards to improve upon the basic strategy rules for specific hands played. For example, with many tens left in the deck, the player may double down in more situations since there is a better chance of making a strong hand.

Virtually all card counting systems do not require the player to remember which cards have been played. Rather, a point system is established for the cards, and the player keeps track of a simple point count as the cards are played out from the dealer.

Depending on the particular blackjack rules in a given casino, basic strategy reduces the house advantage to near 0 with some single-deck games, and less than one percent in a multi-deck game.^[4] Card counting, if done correctly, can give the player an advantage in the other direction, typically ranging from 0 to 2% over the house.^[5] To counter card counting, many casinos switched from a single deck to multiple decks, with the cards dealt out of a container known as a "shoe".

In most US jurisdictions, card counting is legal and is not considered cheating.^[6] However, most casinos have the right to ban players, with or without cause, and card counting is frequently used as a justification to ban a player. Usually, the casino host will simply inform the player that he is no longer welcome to play at that casino. Players must be careful not to signal the fact that they are counting. The use of electronic or other counting devices is usually illegal.

Composition-dependent strategy

Basic strategy is based on a player's point total and the dealer's visible card. A player's ideal decision may depend on the composition of his or her hand, not just the information considered in the basic strategy. For example, a player should ordinarily stand when holding 12 against a dealer 4. However, in a single deck game, the player should hit if his or her 12 consists of a 10 and a 2; this is because the player wants to receive any card other than a 10 if hitting, and the 10 in the player's hand is one less card available to cause a bust for the player or the dealer.^[7]

However, in situations where basic and composition-dependent strategy lead to different actions, the difference in expected value between the two decisions will be small. Additionally, as the number of decks used in a blackjack game rises, both the number of situations where composition determines the correct strategy and the house edge improvement from using a composition-dependent strategy will fall. Using a composition-dependent strategy only reduces house edge by 0.0031% in a six-deck game, less than one tenth the improvement in a single-deck game (0.0387%).^[8]

Shuffle tracking

Techniques other than card counting can swing the advantage of casino blackjack towards the player. All such techniques are based on the value of the cards to the player and the casino, as originally conceived by Edward O. Thorp. ^{[citation needed]} One technique, mainly applicable in multi-deck games, involves tracking groups of cards (aka slugs, clumps, packs) during the play of the shoe, following them through the shuffle and then playing and betting accordingly when those cards come into play from the new shoe. This technique, which is admittedly much more difficult than straight card counting and requires excellent eyesight and powers of visual estimation, has the additional benefit of fooling the casino people who are monitoring the player's actions and the count, since the shuffle tracker could be, at times, betting and/or playing opposite to how a straightforward card counter would. ^{[citation needed]}

Arnold Snyder's articles in Blackjack Forum magazine brought shuffle tracking to the general public. His book, The Shuffle Tracker's Cookbook, mathematically analyzed the player edge available from shuffle tracking based on the actual size of the tracked slug. Jerry L. Patterson also developed and published a shuffle-tracking method for tracking favorable clumps of cards and cutting them into play and tracking unfavorable clumps of cards and cutting them out of play. ^{[9] [10] [11]} Other legal methods of gaining a player advantage at blackjack include a wide variety of techniques for gaining information about the dealer hole-card or the next card to be dealt.

Variants

Pontoon is an English variation of blackjack with significant rule and strategy differences. However, in Australia and Malaysia, Pontoon is an unlicensed version of the American game Spanish 21 played without a hole card; despite the name, it bears no relation to English Pontoon.

Spanish 21 provides players with many liberal blackjack rules, such as doubling down any number of cards (with the option to 'rescue', or surrender only one wager to the house), payout bonuses for five or more card 21's, 6-7-8 21's, 7-7-7 21's, late surrender, and player blackjacks always winning and player 21's always winning, at the cost of having no 10 cards in the deck (though there are jacks, queens, and kings).

21st Century Blackjack (also known as "Vegas Style" Blackjack) is commonly found in many California card rooms. In this form of the game, a player bust does not always result in an automatic loss; there are a handful of situations where the player can still push if the dealer busts as well, provided that the dealer busts with a higher total.

Certain rules changes are employed to create new variant games. These changes, while attracting the novice player, actually increase the house edge in these games. Double Exposure Blackjack is a variant in which the dealer's cards are both face-up. This game increases house edge by paying even money on blackjacks and players losing ties. Double Attack Blackjack has very liberal blackjack rules and the option of increasing one's wager after seeing the dealer's up card. This game is dealt from a Spanish shoe, and blackjacks only pay even money.

The French and German variant "Vingt-et-un" (Twenty-one) and "Siebzehn und Vier" (Seventeen and Four) don't include splitting. An ace can only count as eleven, but two aces count as a Blackjack. This variant is seldom found in casinos, but in private circles and barracks. Card Strategy 2 3 4 5 6 7 8 9 10 J Q K A KO 1 1 1 1 1 1 0 0 -1 -1 -1 -1 -1 Hi-Lo 1 1 1 1 1 0 0 0 -1 -1 -1 -1 -1 Hi-Opt I 0 1 1 1 1 0 0 0 -1 -1 -1 -1 0 Hi-Opt II 1 1 2 2 1 1 0 0 -2 -2 -2 -2 0 Zen Count 1 1 2 2 2 1 0 0 -2 -2 -2 -2 -1 Omega II 1 1 2 2 2 1 0 -1 -2 -2 -2 -2 0

Chinese Blackjack is played by many in Asia, having no splitting of cards, but with other card combination regulations.

Another variant is Blackjack Switch, a version of blackjack in which a player is dealt two hands and is allowed to switch cards. For example, if the player is dealt 10-6 and 10-5, then the player can switch two cards to make hands of 10-10 and 6-5. Natural blackjacks are paid 1:1 instead of the standard 3:2, and a dealer 22 is a push.

Recently, thanks to the popularity of poker, Elimination Blackjack has begun to gain a following. Elimination Blackjack is a tournament format of blackjack.

Many casinos offer optional side bets at standard blackjack tables. For example, one common side-bet is "Royal Match", in which the player is paid if his first two cards are in the same suit, and receives a higher payout if they are a suited queen and king (and a jackpot payout if both the player and the dealer have a suited queen-king hand). Another increasingly common variant is "21+3," in which the player's two cards and the dealer's up card form a three-card poker hand; players are paid 9 to 1 on a straight, flush or three of a kind. These side bets invariably offer worse odds than well-played blackjack.

Blackjack Hall of Fame

In 2002, professional gamblers around the world were invited to nominate great blackjack players for admission into the Blackjack Hall of Fame. Seven members were inducted in 2002, with new inductees every year afterwards. The physical hall of fame is located at the Barona Casino in San Diego, California. Members include Edward O. Thorp, author of the 1960s book Beat the Dealer which proved that the game could be beaten with a combination of basic strategy and card counting; Ken Uston, who popularized the concept of team play; Arnold Snyder, author and editor of the Blackjack Forum trade journal; Stanford Wong, author and popularizer of the "Wonging" technique of only playing at a positive count, and several others.

Notes

Sources

• Beat the Dealer : A Winning Strategy for the Game of Twenty-One, Edward O. Thorp, 1966, ISBN 978-0-394-70310-7
• Blackbelt in Blackjack, Arnold Snyder, 1998 (1980), ISBN 978-0-910575-05-8
• Blackjack: A Winner’s Handbook, Jerry L. Patterson, 2001, (1978), ISBN 0-399-52638-8
• Ken Uston on Blackjack, Ken Uston, 1986, ISBN 978-0-8184-0411-5
• Knock-Out Blackjack, Olaf Vancura and Ken Fuchs, 1998, ISBN 978-0-929712-31-4
• Luck, Logic, and White Lies: The Mathematics of Games, Jörg Bewersdorff, 2004, ISBN 978-1-56881-210-6, 121-134
• Million Dollar Blackjack, Ken Uston, 1994 (1981), ISBN 978-0-89746-068-2
• Playing Blackjack as a Business, Lawrence Revere, 1998 (1971), ISBN 978-0-8184-0064-3
• Professional Blackjack, Stanford Wong, 1994 (1975), ISBN 978-0-935926-21-7
• The Theory of Blackjack, Peter Griffin, 1996 (1979), ISBN 978-0-929712-12-3
• The Theory of Gambling and Statistical Logic, Richard A. Epstein, 1977, ISBN 978-0-12-240761-1, 215-251
• The World's Greatest Blackjack Book, Lance Humble and Carl Cooper, 1980, ISBN 978-0385153829

Regulation in the United Kingdom

• Statutory Instrument 1994 No. 2899 The Gaming Clubs (Bankers' Games) Regulations 1994
• Statutory Instrument 2000 No. 597 The Gaming Clubs (Bankers' Games) (Amendment) Regulations 2000
• Statutory Instrument 2002 No. 1130 The Gaming Clubs (Bankers' Games) (Amendment) Regulations 2002

External links

• Arnold Snyder's Blackjack Forum
• Blackjack Info
• Blackjack Mathematics
• Blackjack Stats
• Blackjack Tactics

Blackjack calculators

• Server based calculator
• Browser based calculator (using JavaScript)
• Card-counting.com - Multiple calculators and charts