Blackjack glossary

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• 3:2 payout The standard payout on a natural: 3 units for every 2 bet.

  A 10 bet on a natural is paid 15. Six decks, H17, DAS and 3:2 give a basic strategy house edge of roughly 0.6%.

  Also called 3 to 2, 3:2.

  See also: 6:5 payout, Natural (blackjack), House edge

• 6:5 payout A reduced payout on a natural: 6 units for every 5 bet.

  A 10 bet on a natural is paid 12 instead of 15. The change adds about 1.4% to the house edge, far more than any other common rule change.

  Also called 6 to 5, 6:5.

  See also: 3:2 payout, Natural (blackjack), House edge

B

• Back counting Counting a shoe without playing and joining only when the count turns favorable.

  Many tables limit this with a no mid-shoe entry rule.

  Also called wonging, wong in.

  See also: Card counting, True count

• Bankroll The money set aside for play, separate from everyday money.

  Also called roll.

  See also: Risk of ruin, Variance, Unit

• Basic strategy The play for each player hand against each dealer upcard that costs the least on average, for a given set of rules.

  Basic strategy uses only your cards and the upcard. It differs a little by rule set and number of decks.

  Also called BS.

  See also: Deviation, Upcard, House edge

• Bet ramp A plan that ties bet size to the true count, betting more when the count is favorable.

  Also called bet spread, spread.

  See also: True count, Card counting, Unit

• Burn card A card discarded unseen, after a shuffle or before dealing.

  Also called burn.

  See also: Shoe, Cut card

• Bust Going over 21, which loses the hand.

  A player who busts loses at once, even if the dealer later busts too. This is the main source of the house edge in blackjack.

  Also called break, too many.

  See also: Hit, Stiff hand, House edge

C

• Card counting Tracking which cards have been played to estimate whether the remaining cards favor the player or the dealer.

  Many tens and aces left favor the player. Counting uses only what is visible at the table and is legal in most places, but casinos may limit a counter's bets or refuse their play. Using a device to help is illegal in many jurisdictions.

  Also called counting.

  See also: Running count, True count, Hi-Lo, Bet ramp

• Cut card A plastic card placed in the shoe to mark where the dealer stops and reshuffles.

  Also called marker card.

  See also: Penetration, Shoe

D

• DAS A rule that lets you double down on a hand created by splitting.

  DAS lowers the house edge slightly and makes splitting small pairs against weak dealer cards more attractive.

  Also called double after split.

  See also: Double down, Split

• Deck A standard 52-card deck, or the number of such decks in play.

  Fewer decks generally favor the blackjack player slightly when other rules are equal.

  Also called pack.

  See also: Shoe, Spanish 21

• Deviation A departure from basic strategy, made when the count passes a set index number.

  Example: with Hi-Lo, standing on 16 against a ten once the true count reaches about 0 (FlopMAX's chart for its default rules, which rounds the true count down, puts it at +1). A list of the most valuable deviations is often called the Illustrious 18.

  Also called index play, index, playing deviation.

  See also: Basic strategy, True count, Hi-Lo

• Double down To double the original bet in exchange for exactly one more card.

  Doubling is strongest when you are likely to finish with a good total and the dealer is weak, such as 11 against a 6. Some tables limit doubling to totals of 9 to 11 or 10 to 11.

  Also called double, DD.

  See also: DAS, Hit, Basic strategy

E

• Early surrender Surrender allowed before the dealer checks for blackjack.

  Because you can escape a dealer ten or ace before a natural is revealed, early surrender is worth much more to the player than late surrender. It is rarely offered.

  Also called ES.

  See also: Surrender, Late surrender

• Edge The average advantage one side holds, as a percentage of the money at risk.

  In casino games the house usually holds the edge. In poker, edge is your expected win rate against the other players after rake.

  Also called advantage, player edge.

  See also: House edge, Expected value

• ENHC European no hole card: the dealer takes a second card only after all players have acted.

  Under ENHC a dealer natural can also take money you added by doubling or splitting, unless the table returns it. Basic strategy is more cautious against a ten or ace, for example not doubling 11 against a ten.

  Also called European no hole card, no hole card.

  See also: Peek, Hole card, Basic strategy

• Even money Taking a 1 to 1 payout on a natural when the dealer shows an ace, instead of risking a push.

  Even money is the same as insuring your blackjack, and for a basic strategy player it costs more on average than playing the hand out.

  See also: Insurance, Natural (blackjack)

• Expected value The average result of a decision if it were repeated many times.

  EV weighs each outcome by its probability. In poker it compares choices: the higher-EV play is better even if it loses this time. In casino games every bet has negative EV equal to its house edge, and the right play is the one that loses least.

  Also called EV.

  See also: House edge, Variance, Long run

F

• Flat bet Betting the same amount every round.

  In craps, the flat bet is also the pass or come bet that the odds bet goes behind.

  Also called flat betting.

  See also: Unit, Odds

G

• Gambler's fallacy The mistaken belief that past independent results change the chance of the next one.

  Five reds in a row do not make black more likely on the next spin.

  Also called Monte Carlo fallacy.

  See also: Scoreboard, Long run

H

• H17 A rule under which the dealer must hit a soft 17.

  H17 adds about 0.2% to the house edge compared with S17, and changes a few basic strategy plays.

  Also called dealer hits soft 17.

  See also: S17, Soft total, House edge

• Hard total A hand with no ace, or with every ace counted as 1.

  A hard 16 such as 10-6 can bust with one card. Compare a soft total, which cannot.

  Also called hard hand, hard.

  See also: Soft total, Bust, Basic strategy

• Hi-Lo A balanced counting system: 2 to 6 count +1, 7 to 9 count 0, tens and aces count -1.

  Hi-Lo is the most widely taught count. Because it is balanced, the running count must be converted to a true count.

  Also called high-low count, plus-minus.

  See also: KO, Omega II, True count

• Hit To take another card.

  Also called draw, take a card.

  See also: Stand, Bust

• Hole card The dealer's face-down card.

  In most US games the dealer takes the hole card at the start and checks it for blackjack when showing an ace or ten-value card.

  Also called dealer hole card, face-down card.

  See also: Peek, Upcard, ENHC

• House edge The average share of each bet the house keeps over the long run, as a percentage.

  A 1.41% house edge means an average cost of 1.41 per 100 bet. It says nothing about any one session, only about the average.

  Also called HE, casino advantage.

  See also: Expected value, Return to player, True odds

I

• Insurance A side bet, offered when the dealer shows an ace, that pays 2 to 1 if the dealer has blackjack.

  Insurance costs up to half the original bet. Without information about the remaining cards it costs more on average than it returns. Card counters take it when the count shows many tens left, classically at a Hi-Lo true count of +3 or higher.

  See also: Even money, True count, Upcard

K

• KO An unbalanced count: 2 to 7 count +1, 8 and 9 count 0, tens and aces count -1.

  Because it is unbalanced, KO is used with the running count directly, with no true count conversion.

  Also called Knock-Out, KO count.

  See also: Hi-Lo, Running count

L

• Late surrender Surrender allowed only after the dealer checks for blackjack.

  If the dealer has a natural you lose the full bet; otherwise you may give up half. It lowers the house edge slightly when used correctly.

  Also called LS.

  See also: Surrender, Early surrender, Peek

• Long run The very large number of trials over which average results approach expected value.

  The long run is far longer than most people expect, often tens or hundreds of thousands of hands or rounds.

  See also: Expected value, Sample size, Variance

N

• Natural (blackjack) An ace and a ten-value card as the first two cards, a total of 21.

  A natural beats any other 21. It usually pays 3 to 2; some tables pay only 6 to 5. If the dealer also has a natural, the hand is a push.

  Also called blackjack, natural, snapper.

  See also: 3:2 payout, 6:5 payout, Push

O

• Omega II A level-two balanced count: 2, 3 and 7 count +1; 4, 5 and 6 count +2; 9 counts -1; tens count -2.

  Eights and aces count 0, and aces are often tracked separately. It is more accurate than Hi-Lo but harder to keep.

  Also called Omega 2.

  See also: Hi-Lo, KO

P

• Payout odds What a winning bet pays relative to the stake.

  "To 1" means you keep the stake plus the payout: 5 to 1 on 10 returns 60. "For 1" includes the stake: 5 for 1 on 10 returns 50.

  Also called payout, to 1, for 1.

  See also: True odds, House edge

• Peek The dealer checking the hole card for blackjack when the upcard is an ace or ten-value card.

  With a peek, a dealer natural ends the hand at once and you lose only the original bet, never doubles or splits.

  Also called dealer peek, check for blackjack.

  See also: Hole card, ENHC, Late surrender

• Penetration How much of the shoe is dealt before the reshuffle, as a percentage.

  If the cut card sits 1.5 decks from the end of a 6-deck shoe, penetration is 75%. Deeper penetration makes the count more informative.

  Also called pen, deck penetration.

  See also: Shoe, Cut card, True count

• Probability How likely an outcome is, from 0 (never) to 1 (certain), often written as a percentage.

  Probability and odds describe the same thing differently: a 25% chance is 3 to 1 against.

  Also called chance.

  See also: True odds, Expected value

• Push A tie in which the bet is returned without a win or loss.

  Also called tie, standoff.

  See also: Natural (blackjack), Bar 12

R

• Resplit aces A rule that lets you split again if a split ace receives another ace.

  Also called RSA.

  See also: Split, DAS

• Return to player The average share of money bet that comes back, equal to 100% minus the house edge.

  Also called RTP, payback.

  See also: House edge, Expected value

• Risk of ruin The chance of losing an entire bankroll before reaching a goal or the long run.

  It rises with variance and bet size relative to bankroll, and is certain over time for any negative-EV game played without end.

  Also called RoR.

  See also: Bankroll, Variance

• Running count The sum of the tag values of every card seen since the last shuffle.

  Also called RC.

  See also: True count, Hi-Lo, Card counting

S

• S17 A rule under which the dealer stands on every 17, including soft 17.

  Also called dealer stands on soft 17, stands on all 17s.

  See also: H17, Soft total

• Sample size The number of hands, rolls or spins in a set of results.

  Small samples are dominated by variance; they say little about whether a strategy is good.

  See also: Long run, Standard deviation

• Shoe A box holding several shuffled decks from which cards are dealt.

  Blackjack shoes commonly hold 6 or 8 decks; punto banco uses an 8-deck shoe.

  Also called dealing shoe.

  See also: Deck, Cut card, Penetration

• Side bet An optional extra wager on a specific outcome, separate from the main bet.

  Side bets usually carry a much higher house edge than the main game.

  Also called side bets.

  See also: House edge, Insurance, Player pair / Banker pair

• Soft total A hand with an ace counted as 11 without going over 21.

  Ace-6 is soft 17. A soft hand cannot bust on the next card, because the ace can drop back to 1.

  Also called soft hand, soft.

  See also: Hard total, H17, Double down

• Spanish 21 A blackjack variant dealt from Spanish decks, which have the four ten-spot cards removed but keep the face cards.

  Removing the 10s hurts the player, so the game adds player-friendly rules such as a player 21 always winning and late surrender. Basic strategy differs from standard blackjack.

  See also: Deck, Basic strategy, Late surrender

• Split To turn a pair into two separate hands by adding a second bet equal to the first.

  Always splitting aces and eights and never splitting tens or fives are well-known parts of basic strategy. Split aces usually receive only one card each.

  Also called splitting, split pairs.

  See also: Resplit aces, DAS, Basic strategy

• Stand To take no more cards and keep the current total.

  Also called stay, stick.

  See also: Hit, Stiff hand

• Standard deviation The square root of variance, in the same units as the results.

  Over many trials, results land within about two standard deviations of the expectation roughly 95% of the time.

  Also called SD, std dev.

  See also: Variance, Sample size

• Stiff hand A hard total of 12 to 16, which can bust with one hit.

  Also called stiff.

  See also: Hard total, Bust, Stand

• Surrender To give up the hand and lose half the bet instead of playing it out.

  Most surrender offered today is late surrender. Basic strategy uses it in only a few spots, such as hard 16 against a dealer 9, ten or ace.

  Also called give up half.

  See also: Late surrender, Early surrender

T

• True count The running count divided by the number of decks left to play.

  A running count of +6 with 3 decks left is a true count of +2. With a balanced count, each point of true count shifts the edge by roughly half a percent.

  Also called TC.

  See also: Running count, Deviation, Bet ramp

U

• Unit A standard bet size used to measure bets and results independently of stakes.

  Also called betting unit.

  See also: Bankroll, Bet ramp, Big blind (unit)

• Upcard The dealer's face-up card, which every basic strategy decision depends on.

  Also called dealer up card, dealer showing.

  See also: Hole card, Basic strategy

V

• Variance How widely actual results spread around the expected value.

  High variance means big swings in both directions. Correct decisions can still produce losing sessions.

  Also called swings.

  See also: Standard deviation, Expected value, Risk of ruin