General glossary

B

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

  Also called roll.

  See also: Risk of ruin, Variance, Unit

  Poker · Blackjack · Roulette · Craps · Baccarat

C

• Correct The top FlopMAX grade: the best play, or one the reference plays with the hand at least half the time.

  Every graded decision on FlopMAX gets one of four levels: Correct, Mostly correct, Incorrect or Whiff.

  Preflop, Correct is a play the reference ranges make with the hand at least half the time. Postflop, against an exact solve, it is a move within 1% of the pot of the best one, or any move the solve plays at least 10% of the time with the hand.

  Also called correct play.

  See also: Mostly correct, Incorrect, Whiff

E

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

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

  Blackjack · Roulette · Craps · Baccarat

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

  Blackjack · Roulette · Craps · Baccarat

H

• 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

  Blackjack · Roulette · Craps · Baccarat

I

• Incorrect The third FlopMAX grade: a real mistake, which ends a streak.

  Postflop, it means giving up between 5% and 20% of the pot.

  See also: Mostly correct, Whiff, Correct

L

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

M

• Mostly correct The second FlopMAX grade: close to the best play, with a little given up; it keeps a streak going.

  Preflop, it is a play the reference mixes in: one it makes with the hand 10% to 50% of the time. Postflop, against an exact solve, it means giving up between 1% and 5% of the pot.

  See also: Correct, Incorrect, Whiff

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

  Blackjack · Roulette · Craps · Baccarat

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

R

• 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

  Blackjack · Roulette · Craps · Baccarat

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

S

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

• 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

  Blackjack · Baccarat

• 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

  Poker · Blackjack · Roulette · Craps · Baccarat

T

• True odds The real chance of an outcome stated as odds against it.

  A 7 in craps rolls 6 ways of 36, true odds 5 to 1. Any 7 pays 4 to 1; the gap is the house edge.

  Also called actual odds.

  See also: Payout odds, House edge, Odds

  Roulette · Craps · Baccarat

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)

  Poker · Blackjack · Roulette · Craps · Baccarat

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

  Poker · Blackjack · Roulette · Craps · Baccarat

W

• Whiff The lowest FlopMAX grade: a large mistake in a spot that was not close; it ends a streak.

  Postflop, it means giving up more than 20% of the pot. Preflop, it is a play the reference makes rarely (under 10% of the time) or never, in a spot that is not a close decision. In blackjack, it means giving up more than 10% of the bet.

  See also: Incorrect, Correct, Mostly correct