Roulette: how it works

The wheel

A roulette wheel has numbered pockets. The dealer spins the wheel one way and a small ball the other. When the ball settles in a pocket, that number wins.

There are two common wheels:

• American: 38 pockets, numbered 1 to 36 plus 0 and 00.
• European: 37 pockets, numbered 1 to 36 plus a single 0.

The numbers 1 to 36 are half red and half black. The zeros are green. The numbers are not in order around the wheel; they are spread out so that red and black alternate and high and low numbers mix.

The layout

You place bets on a table layout, not on the wheel. The layout shows 1 to 36 in a grid of three columns and twelve rows, with the zero or zeros at the top. Along the sides are boxes for the larger groups: the three dozens, the three columns, red or black, odd or even, and low (1 to 18) or high (19 to 36).

A spin

1. Players place chips on the layout.
2. The dealer spins the wheel and launches the ball, then calls "no more bets" as the ball begins to slow.
3. The ball lands. The dealer marks the winning number.
4. Losing bets are cleared and winning bets are paid. A winning bet usually stays on the layout for the next spin unless you take it down.

The bets

Inside bets go on the numbers in the grid. Outside bets go in the boxes around it. A payout of 35 to 1 means a winning bet of 1 wins 35 and you keep your 1.

The zeros are not red, black, odd, even, low or high, and they are not in any dozen or column. When a zero comes up, every outside bet loses (unless the table uses one of the rules below).

Payouts and true odds

The true odds of a bet compare the ways it loses to the ways it wins. On an American wheel, a single number has 1 way to win and 37 ways to lose, so the true odds are 37 to 1. The bet pays 35 to 1.

Every payout on the layout is set as if the zeros were not there. On a wheel with only 1 to 36, a straight-up bet would be 35 to 1 against, and it would pay exactly that. The zero, or the two zeros, are the pockets the house is not paying for. That gap is where the House edge comes from.

The house edge

The house edge is the share of each bet the house keeps on average over a very Long run. It does not tell you what happens on one spin.

On the American wheel, a bet of 1 on red loses about 5.3 hundredths on average. On the European wheel, about 2.7 hundredths. The single-zero wheel costs about half as much on every bet.

On a given wheel, a single number and a bet on red cost the same on average. What changes is how bumpy the results are. A straight-up bet loses most spins and pays 35 to 1 now and then; an even-money bet wins about half the time and pays little. That spread of results is Variance, and it is the real difference between the bets.

FlopMAX uses the American wheel by default. The European wheel is in the game's settings.

La partage and en prison

Some European tables soften the zero for even-money bets (red or black, odd or even, low or high):

• La partage: when 0 comes up, you get back half of each even-money bet.
• En prison: when 0 comes up, your even-money bet stays on the table for the next spin. If it wins then, you get it back with no win. If it loses, it is gone.

Either rule cuts the edge on those bets about in half. With la partage it is 1.35%. With en prison it is about 1.4%, depending on what happens if 0 comes up again while a bet is held. Other bets are not affected.

Betting systems

Every spin is independent. The wheel has no memory, so a run of ten reds does not make black more likely next. Believing it does is the gambler's fallacy.

Betting systems change how much you bet and when, such as doubling after each loss. They cannot change the payout of any bet or the chance that it wins, so every bet you make still carries the same house edge. A system changes the pattern of results, not the average.