The wheel that has one extra pocket
A roulette wheel with 38 slots is not a detail you notice later. It is the single fact that changes the price of every bet you place. The extra slot is a second green pocket, the double zero, and it sits opposite the single zero on the wheel. The numbered pockets still run 0 through 36, but the American layout adds the 00 pocket to make 38 positions in total.
That one additional pocket is why an American wheel charges a higher house edge than a European wheel with 37 pockets. The house edge is the mathematical advantage the operator holds on a given game, expressed as a percentage of each wager, and it does not change from spin to spin. On a 38-slot wheel, the two green pockets are where the house collects on bets that pay as if those pockets did not exist.
Reading the layout before you buy in
When you sit down at a table with a 38-slot wheel, the felt layout shows two betting areas. The inside area holds the individual numbers in a grid, and the outside area holds the group bets. Every bet you can make is printed on that layout, along with its payout. You do not need to memorise the wheel's pocket order to play, but you should look at the layout long enough to see where the 0 and 00 sit, because they are not covered by any of the red-or-black, odd-or-even, or high-or-low outside bets.
Buy-in works like any table game. You place cash on the felt, the dealer exchanges it for roulette chips, and those chips are normally a distinct colour so the dealer can tell your stack from every other player's. The chips have no value away from that table; you cash them back before you leave.
The sequence of a round
A round of roulette moves through a fixed order. First the dealer clears the previous round's losing bets and pays the winners. Then the dealer opens the betting window, and players place chips on the layout. The dealer spins the wheel in one direction and sends the ball travelling the opposite way around the rim. At some point the dealer calls no more bets, and from that moment the layout is frozen. The ball loses speed, drops into a pocket, and the dealer marks the winning number. Losing bets are cleared, winning bets are paid according to the printed odds, and the next round begins.
The call of no more bets is the decision point that matters most for a new player. Anything placed after that call is returned or refused. If you are still deciding where to bet while the wheel is already slowing, you are too late.
Inside bets and the odds they pay
Inside bets are placed on the numbered grid. A straight-up bet covers one number. A split covers two adjacent numbers. A street covers three numbers in a row, a corner covers four, and a six-line covers six. The payouts are printed on the layout and are higher for bets that cover fewer numbers, because fewer numbers means a lower chance of winning on that spin.
None of those payouts changes the house edge. The edge comes from the wheel having 38 pockets while the payouts are calculated as if there were 36. A straight-up bet on an American wheel pays 35 to 1, but there are 38 possible pockets, so the house edge on that bet is higher than on a 37-pocket European wheel. The same arithmetic applies to every inside bet.
Outside bets: the lower-edge side of the layout
Outside bets sit around the numbered grid and cover larger groups. Red or black, odd or even, and high or low each cover 18 numbers and pay even money. Dozens and columns cover 12 numbers each and pay 2 to 1. These bets lose on both zero pockets, which is why the green pockets matter so much on a 38-slot wheel.
The comparison that matters for a new player is not inside versus outside in general, but how each bet's payout relates to the number of pockets it covers. The table below sets out the main bet types on an American layout, how many pockets each covers, and what the printed payout is.
| Bet type | Pockets covered | Printed payout | What the zeros do |
|---|---|---|---|
| Straight-up | 1 | 35 to 1 | Lose unless the number is 0 or 00 |
| Split | 2 | 17 to 1 | Lose unless one of the numbers is 0 or 00 |
| Street | 3 | 11 to 1 | Lose |
| Corner | 4 | 8 to 1 | Lose |
| Six-line | 6 | 5 to 1 | Lose |
| Red or black / odd or even / high or low | 18 | 1 to 1 | Lose on both 0 and 00 |
| Dozen or column | 12 | 2 to 1 | Lose on both 0 and 00 |
Notice the pattern: the payout is always a little short of what the number of covered pockets would justify on a wheel with no zeros. That shortfall is the house edge, and on a 38-slot wheel it is larger than on a 37-slot wheel because there are two pockets that no outside bet covers.
Where the double zero shows up in the edge
House edge and RTP are complements: they sum to 100% for the same game. RTP is a theoretical percentage of total wagered money a game returns to players over a very large number of spins or hands, and it is a long-run statistical average, not a per-session guarantee. On an American wheel, the extra pocket moves the RTP down and the house edge up compared with a single-zero wheel.
The difference is easiest to see on an even-money bet. On a European wheel, an even-money bet covers 18 of 37 pockets. On an American wheel, the same bet covers 18 of 38 pockets, but the payout is still 1 to 1. The two green pockets are the reason the American layout is the more expensive version of the same game. That is not a prediction about your next spin; it is the built-in arithmetic of the wheel.
Roulette has no strategy chart, and that is the point
Some table games publish basic-strategy charts that derive from the specific rule set in use. Blackjack is the clearest example: the correct play on a given hand changes with the number of decks, whether the dealer stands on soft 17, and which doubling and splitting rules apply. Roulette has no equivalent chart, because there is no decision after the ball is released that changes the probability of any pocket.
What you can choose is which bets to place, and that choice changes the expected rate of loss. A straight-up bet and an even-money bet on the same 38-slot wheel carry the same house edge, but they distribute wins and losses very differently. The straight-up bet wins rarely and pays a lot; the even-money bet wins close to half the time and pays even money. Neither choice changes the edge, but the pattern of your session will feel completely different.
Procedural mistakes that cost new players
The first mistake is betting after the dealer calls no more bets. The call is not a suggestion, and a chip that lands late will be returned or refused. If you want to bet on a round, place the chip while the betting window is open and keep your hands off the layout once the ball is moving.
The second mistake is touching your chips after the winning number is called. The dealer pays winners and clears losers in a specific order, and any movement on the layout makes that job harder. Wait for the dealer to finish the settlement before you reach for a payout or add chips for the next round.
The third mistake is treating the two zero pockets as an afterthought. On a 38-slot wheel, every outside bet loses when either zero appears, and that is a larger share of the wheel than on a single-zero layout. Before you place an even-money bet, look at the wheel and see both green pockets for what they are: the reason the payout is lower than the true odds.
What changes if the wheel has 37 slots instead
If you later sit at a table with a single-zero wheel, the game is the same in structure but different in price. The European wheel has 37 pockets, and the removal of the double zero lowers the house edge on every bet. The payouts printed on the layout are the same, but the probability of a zero appearing is smaller.
That is why the first question to answer at any roulette table is not which bet to place, but which wheel you are playing. The number of slots around the rim is printed nowhere on the felt, but you can see it on the wheel itself. Count the green pockets. One green pocket means 37 slots; two green pockets means 38. The rest of the session follows from that.
FAQ
Does the 00 pocket change the payout on a straight-up bet?
No. A straight-up bet pays 35 to 1 on both American and European layouts. What changes is the probability of winning, because the 00 pocket adds one more losing position to the wheel while the payout stays the same.
Can I bet on 0 and 00 together?
On most American layouts you can place a split bet covering 0 and 00, and it pays 17 to 1. Some tables also offer a five-number bet covering 0, 00, 1, 2, and 3, but that bet carries a higher house edge than any other bet on the layout, so it is worth checking the printed payout before you use it.
Why do some roulette tables have 38 slots and others 37?
The 38-slot wheel is the American layout, which adds a double-zero pocket to the standard 37-pocket European wheel. The extra pocket increases the house edge on every bet, so the two wheels are the same game at two different prices. The wheel itself shows you which one you are playing before you place a chip.
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