Roulette glossary

A

• American roulette A wheel with 38 pockets: 1 to 36, 0 and 00.

  Every bet but one has a 5.26% house edge. The five-number bet is worse at 7.89%.

  Also called double-zero roulette, American wheel.

  See also: European roulette, Double zero, Basket

B

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

  Also called roll.

  See also: Risk of ruin, Variance, Unit

• Basket The American-wheel bet on 0, 00, 1, 2 and 3, paying 6 to 1.

  It is the worst bet on the American wheel: its house edge is 7.89%, against 5.26% for every other bet there.

  Also called top line, five-number bet, five number.

  See also: American roulette, First four, House edge

C

• Column A bet on one of the three vertical columns of 12 numbers, paying 2 to 1.

  Also called columns.

  See also: Dozen, Outside bet

• Corner A bet on four numbers that meet at a corner, paying 8 to 1.

  Also called square, quad.

  See also: Street (roulette), Six line, First four

D

• Double zero The second green pocket on an American wheel, which nearly doubles the house edge.

  Also called 00.

  See also: American roulette, Single zero

• Dozen A bet on 1 to 12, 13 to 24 or 25 to 36, paying 2 to 1.

  Also called dozens.

  See also: Column, Outside bet

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

• En prison A rule that holds an even-money bet for one more spin when the ball lands on zero.

  If the next spin wins, the bet is returned without a payout. The effect is close to la partage, about 1.35% on a single-zero wheel.

  See also: La partage, European roulette

• European roulette A wheel with 37 pockets: 1 to 36 and a single 0.

  Every bet has a 2.70% house edge, about half the American figure. Some tables add la partage or en prison on even-money bets.

  Also called single-zero roulette, European wheel.

  See also: American roulette, Single zero, La partage

• 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

• First four A European-wheel bet on 0, 1, 2 and 3, paying 8 to 1.

  See also: Basket, Corner

• 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

• High/low A bet on 1 to 18 or 19 to 36, paying 1 to 1.

  Also called 1-18, 19-36, manque/passe.

  See also: Red/black, Odd/even

• 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

• Inside bet A bet on a single number or a small group of numbers on the numbered grid.

  Inside bets pay more and hit less often than outside bets, but on a single-zero or double-zero wheel most carry the same house edge.

  Also called inside bets.

  See also: Outside bet, Straight up, Split (roulette), Corner

L

• La partage A rule returning half of an even-money bet when the ball lands on zero.

  On a single-zero wheel it lowers the house edge on even-money bets to about 1.35%. Some American tables offer a similar rule on 0 and 00.

  Also called partage, surrender (roulette).

  See also: En prison, European roulette

• 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

O

• Odd/even A bet on whether the winning number is odd or even, paying 1 to 1; zero is neither.

  Also called odd or even, impair/pair.

  See also: Red/black, High/low

• Outside bet A bet on a large group of numbers placed around the edge of the layout.

  Red/black, odd/even, high/low, dozens and columns are outside bets. A zero makes all of them lose, unless a la partage or en prison rule covers even-money bets.

  Also called outside bets.

  See also: Inside bet, Red/black, Dozen, Column

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

• Pocket One of the numbered compartments on the wheel where the ball comes to rest.

  Also called slot.

  See also: American roulette, European roulette

• 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

R

• Red/black A bet on the color of the winning number, paying 1 to 1.

  Eighteen numbers are red and eighteen black; the zeros are green and make the bet lose.

  Also called red or black, color bet.

  See also: Odd/even, High/low, Outside bet

• 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

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

• Single zero The one green pocket on a European wheel, where all outside bets lose.

  Also called 0.

  See also: European roulette, Double zero

• Six line A bet on two adjacent rows, six numbers, paying 5 to 1.

  Also called double street, line.

  See also: Street (roulette), Corner

• Split (roulette) A bet on two adjacent numbers, paying 17 to 1.

  Also called split, a cheval.

  See also: Straight up, Street (roulette)

• 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

• Straight up A bet on one number, paying 35 to 1.

  Also called single number.

  See also: Split (roulette), Inside bet

• Street (roulette) A bet on a row of three numbers, paying 11 to 1.

  Also called street.

  See also: Split (roulette), Six line

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

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)

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