Blackjack Guide

In casino blackjack, the dealer faces one to seven players from behind a kidney-shaped table. Each player plays his hand independently against the dealer. At the beginning of each round, the player places a bet in the “betting box” and receives an initial hand of two cards.
The object of the game is to get a higher card total than the dealer, but without going over 21 which is called “busting” or “too many.” (The spot cards count 2 to 9; the 10, jack, queen, and king count as ten; an ace can be either 1 or 11.) The player goes first and plays his hand by taking additional cards if he desires.

If he busts, he loses. Then the dealer plays her hand. If the dealer busts, she loses to all remaining players. If neither busts, the higher hand total wins. In case of a tie, no one wins – the hand is a “push.” It is possible for the dealer to lose to some players but still beat other players in the same round.
Example of a Blackjack game. The top half of the picture shows the beginning of the round, with bets placed and an initial two cards for each player. The bottom half shows the end of the round, with the associated losses or payoffs.
Cards are dealt in two ways, either from one or two hand-held decks, or from a box containing four to eight decks called a “shoe.” When dealt by hand, the player’s two initial cards are face-down, while the dealer has one face-up card called the “upcard” and one face-down card called the “hole card.” (In European blackjack, the hole card is not actually dealt until the players all play their hands.) When dealt from a shoe, all player cards are normally dealt face-up, with minor exceptions.
It shouldn’t matter to the player whether his cards are dealt face-down or face-up since the dealer must play according to predetermined rules. If the dealer has less than 17, she must hit. If the dealer has 17 or more, she must stand (take no more cards), unless it is a “soft 17″ (a hand that includes an ace valued as “11,” for example a hand consisting of Ace+6, or Ace+2+4). With a soft 17, the dealer follows the casino rules printed on the blackjack table, either to “hit soft 17″ or to “stand on all 17’s.”
The highest possible hand is a “blackjack” or “natural,” meaning an initial two-card total of 21 (an ace and a ten-value card). A player blackjack is an automatic winner unless the dealer also has blackjack, in which case the hand is a “push” (a tie). When the dealer upcard is an ace, the player is allowed to make a side bet called “insurance,” supposedly to guard against the risk that the dealer has a blackjack (i.e., a ten-value card as her hole card).
The insurance bet pays 2-to-1 if the dealer has a blackjack. Whenever the dealer has a blackjack, she wins against all player hands except those that also have a blackjack (which are a “push”).
The minimum and maximum bets are posted on the table. The payoff on most bets is 1:1, meaning that the player wins the same amount as he bets. The payoff for a player blackjack is 3:2, meaning that the casino pays $3 for each $2 originally bet. (There are some single-deck games which pay only 6:5 for a blackjack.)
Player decisions
After receiving his initial two cards, the player has four standard options: he can “Hit,” “Stand,” “Double Down,” or “Split a pair.” Each option requires the use of a hand signal. At some casinos or tables, the player may have a fifth option called “Surrender.”
Hit: Take another card.
signal: (handheld) scrape cards against table; (face up) touch finger to table Stand: Take no more cards, also “stick” or “stay”.
signal: (handheld) slide cards under bet; (face up) move hand horizontally Doubledown: On his first two cards, the player may “double down,” i.e., “double” his bet and receive only one card face “down.”

To do this he moves a second bet equal to the first into the betting box next to his original bet. (If desired, the player is usually allowed to “double down for less,” although this is not a good idea.)
signal: place additional chips next to (not on top of) original bet, make “one finger” sign
Split a pair: If his first two cards are a “pair,” meaning two cards of the same value, the player can “split the pair.” To do this, he moves a second bet equal to the first into the betting box next to his original bet. The dealer splits the cards to create two hands, placing one bet with each hand. The player then plays two separate hands.
signal: place additional chips next to (not on top of) original bet, make “two fingers” sign
Surrender: Some casinos offer a fifth option called “Surrender.” After the dealer has checked for blackjack, the player may “surrender” by giving up half his bet and not playing out the hand.
signal: There is no commonly accepted hand signal; it is just done verbally. The reason for requiring hand signals is to assist the “eye in the sky,” a person or video camera located above the table but concealed behind one-way glass.

It is used in order to protect the casino against dealers or players who cheat. (It may also be used to protect the casino against card-counters, even though card-counting is not illegal.)
The player can take as many hits as he wants (except on a “double down”). However, if he busts, he loses that hand. After all the players have finished making their decisions, the dealer then reveals her hole card and plays out her hand according to predetermined rules.
Rule variations and the “house advantage”
The blackjack player will encounter many rule variations which affect the house advantage and therefore affect his chances of winning. Some rules are determined by law or regulation, others by the casino itself. Not all rules are posted, so the player may have to ask either beforehand or when the situation occurs. Over 100 variations exist.
The casino has a “house advantage” at blackjack just as it does at any other casino game. If a particular casino game has a house advantage of 5%, it means that – over the long run – the casino will win about 5% of any initial bet. As long as the blackjack player uses the best possible strategy (a strategy which is known as “Basic Strategy”), the house advantage in blackjack is less than 1%. This is very favorable to the player compared to other casino games. Of course, many blackjack players do not know Basic Strategy or do not follow it, so the true house advantage in those cases is much higher.
Dealer hits soft 17?
Each casino has a rule about whether or not the dealer hits soft 17, a rule which is printed on the table itself. In the “S17″ game, the dealer stands on all 17s. In the “H17″ game, the dealer hits on soft 17s. Of course, she always stands on hard 17s. In either case, the dealer has no choice; she either must or must not hit. The “Hit soft 17″ game is substantially less favorable to the player with about a 0.2% higher house advantage.
Surrender
Some casinos offer a favorable option called “surrender,” which allows the player to give up half his bet and not play out the hand. This option is sometimes referred to as “late” surrender because it occurs after the dealer has checked her hole card for a blackjack. (When casinos first opened in Atlantic City, the surrender option was available before the dealer checked for blackjack – a rule highly advantageous to the player – but this “early surrender” option soon disappeared.) Early Surrender variations still exist in several countries.
Resplit to nn
If the player splits a pair other than aces and a third card of that value appears, the player can usually resplit by putting up another bet equal to the original bet. Then there will be three bets on the table and three separate hands. Some casinos allow unlimited resplitting of cards other than aces, while others may limit it to a certain number of hands, such as four hands (for example, “resplit to 4″).
Resplit aces
When the player’s first two cards are two aces, the player may split them once. If a third ace appears, however, it cannot be resplit in most casinos. If resplitting aces is allowed, this is favorable to the player.
Double after split
After splitting a pair, some casinos allow the player to “double down” on each of the new two-card hands. This is called “double after split” (DAS) and provides an advantage to the player of about 0.12%.
Double on 10 or 11 only
Often called “Reno” rules, this rule restricts the player to doubling down only on an initial player total of 10 or 11 (sometimes 9, 10, or 11). It prevents doubling on soft hands such as soft 17 (ace-6), and is unfavorable for the player. It increases the house advantage by about 0.20%.
European no-hole-card rule
In some places, the dealer does not receive a hole card, but if the dealer is later found to have blackjack, the player loses only his original bet but not any additional bets (doubles or splits). This has the same advantage as the usual game, and as such does not change basic strategy.
Altered payout for blackjack
In some places, a blackjack pays only 6:5 or even 1:1 instead of the usual 3:2. This is the most unfavorable variation, increasing the house edge significantly more than any other player restriction. The 1:1 payout for video blackjack is a key reason why it has never approached the table version in terms of popularity.

Dealer wins ties
This is catastrophic to the player, though rarely used in standard Blackjack. It is sometimes seen in “blackjack-like” games.
Five card charlie/Five card trick
With this rule, the player always wins when five cards have been drawn without busting, unless there is a blackjack on the table.
Insurance
If the dealer’s upcard is an ace, the player is offered the option of taking Insurance before the dealer checks her ‘hole card’.
Insurance is a side bet of up to half the original bet placed on a special portion of the table usually marked “Insurance Pays 2 to 1″. This side bet is offered only when the dealer’s exposed card is an ace. The idea is that the dealer’s second card has a fairly high probablility (nearly one-third) to be ten-valued, giving the dealer a blackjack and a certain loss for the player.
It is attractive (although not necessarily wise) for the player to insure against this possibility by making an “insurance” bet, which pays 2-to-1 if the dealer has a blackjack, in which case the “insurance proceeds” will make up for the concomitant loss on the original bet.

Of course the insurance bet is forfeited if the dealer does not have blackjack, although the player can still win or lose on the original bet. Insurance is a poor bet for the player unless he is counting cards, because the casino has a theoretical house advantage of 7.69% (“infinite deck”).
The theoretical house advantage is easy to calculate, since the player is essentially betting that the dealer’s hole card is a ten-value card. To calculate it, we can use the example of a player with an original bet of $20, the dealer has an ace, and the player takes insurance for $10.

In an infinite deck, 4/13 of the cards are “tens” (10, J, Q, or K). In theory, the insurance bet will lose 9/13 of the time for minus $90 and will win 4/13 of the time for plus $80, giving a net loss of $10 for 13 hands. The average loss is $0.77 per hand ($10/13), or 7.69%. Therefore, taking insurance is a poor bet for the player (unless he is counting cards).

The odds on the Insurance bet are not improved if the player has a blackjack — it’s still a poor bet. Insurance is simply a side-bet that the dealer has a ten-value hole card, regardless of the player’s original cards.

We can use the same example, where the player has a blackjack on his original bet of $20, the dealer has an ace, and the player takes insurance for $10. The two bets are completely separate. The player can expect on average to win $20.77 for his blackjack, since the original bet wins 9/13 of the time for a total of $270 (9 x $30) and ties 4/13 of the time for a gain of zero, for an average gain of $20.77 per hand ($270/13).

Meanwhile, the insurance side bet of $10 is calculated separately and loses $0.77 on average. Therefore, on average, the player would win $20.77 for his blackjack on his original bet, and would lose $0.77 on the $10 insurance bet, if he takes insurance. The insurance bet is still not worthwhile (unless, again, the player is counting cards).
A variation on this is that some casinos or dealers may offer the player what they call “even money” by offering to pay out a player’s blackjack immediately at 1:1 when the dealer’s upcard is an ace.

Taking even money has the same expected payout as taking insurance; the player’s expectation for the “even money” option is $20.00, instead of an average of $20.77, so it’s not a favorable bet (unless the player is counting 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 her hole card over a small mirror or electronic sensor on the tabletop in order to check whether she has a blackjack. This practice minimizes the risk of inadvertently revealing the hole card, which may give the sharp-eyed player a considerable advantage.