Before you buy in, check which wheel is on the table
The first thing to look at when you sit down at a roulette table is not the felt colour or the minimum bet sign. It is the wheel itself, because the number of pockets on the wheel changes the arithmetic of every bet you can make. A European wheel carries 37 pockets: the numbers 1 through 36 plus a single green zero. An American wheel carries 38 pockets: the same 1 through 36, a single zero, and a second green pocket marked double zero. The difference of one pocket sounds trivial until you realise that the casino's entire edge on most roulette bets comes from the presence of those green pockets.
Roulette numbers run 0-36, and the zero is not a neutral space. When the ball lands in zero, the even-money outside bets such as red or black, odd or even, and high or low all lose on a standard layout. That is the mechanism by which the house edge operates. The more zero pockets a wheel has, the more often those outside bets lose without any compensating increase in what they pay.
What the 37 and 38 pockets mean
The wheel is a physical device, but the game is a mathematical one. Every pocket has the same chance of catching the ball on a fair spin, so the probability of any single number winning is one divided by the total number of pockets. On a European wheel that is 1 in 37. On an American wheel it is 1 in 38. The payout for a straight-up bet on a single number is fixed at 35 to 1 on both wheels. That mismatch between the true odds and the payout odds is where the house edge lives.
RTP and house edge are complements: they sum to 100% for the same bet under the same rule set. If a bet returns a theoretical RTP of 97.Suppose the house edge on that bet is 2.7%. The extra double-zero pocket on an American wheel pushes the house edge higher on most bets, because the payout schedule stays the same while the probability of winning drops.
| Feature | European wheel | American wheel |
|---|---|---|
| Total pockets | 37 | 38 |
| Numbered pockets | 1-36 | 1-36 |
| Zero pockets | One (single zero) | Two (single and double zero) |
| Probability of a single number winning | 1 in 37 | 1 in 38 |
| Payout for a straight-up number bet | 35 to 1 | 35 to 1 |
| House edge on most bets | Lower | Higher |
How a round moves from buy-in to settlement
You buy in by placing cash or chips on the table, and the dealer exchanges them for roulette chips in a colour assigned to you alone at that table. These chips have no value printed on them and cannot be used at other tables; you cash them back at the same table when you finish. The dealer announces that bets are open, and players place chips on the layout. You may place multiple bets on a single spin, and the table minimum applies to the total of your outside bets or to each inside bet, depending on the house rules posted at the table.
Once the ball is spinning, the dealer calls no more bets, and any chip placed after that call is too late. The ball settles into a pocket, the dealer marks the winning number on the layout, and losing bets are cleared first. Winning bets are then paid, and the cycle repeats. Your roulette chips remain on the table until you ask to colour up, at which point the dealer exchanges them back for value chips you can take to the cashier.
The main bet types and how their edges differ
Roulette bets fall into two families. Inside bets sit on the numbered grid and cover specific numbers or small groups of them. Outside bets sit around the grid and cover broad categories. The two families have different payout schedules, different probabilities, and in some rule sets different house edges. On a European wheel, the standard house edge on most bets is the same, but an American wheel changes the picture because the double zero adds a losing pocket to every category.
| Bet type | What it covers | Payout | What changes with the wheel |
|---|---|---|---|
| Straight-up | One single number | 35 to 1 | Probability drops from 1 in 37 to 1 in 38 on an American wheel |
| Split | Two adjacent numbers | 17 to 1 | Same payout, lower probability on American wheel |
| Street | Three numbers in a row | 11 to 1 | Same payout, lower probability on American wheel |
| Red or black | 18 numbers of one colour | 1 to 1 | Zeros are green, so they lose on both wheels; American wheel has two losing green pockets |
| Odd or even | 18 numbers | 1 to 1 | Zeros lose; extra zero increases the house edge |
| High or low | 1-18 or 19-36 | 1 to 1 | Zeros lose; extra zero increases the house edge |
Some European tables offer a rule variation called la partage or en prison on even-money bets. When the ball lands in zero, the player either receives half the bet back or has it held for the next spin. This reduces the house edge on those specific even-money bets, but it does not change the edge on inside bets. The rule is printed on the table layout or posted on a placard, and it is worth checking before you sit down, because it only applies where the house has chosen to offer it.
What a strategy chart does and does not do
Roulette is not a game where a published strategy chart changes the underlying mathematics the way basic strategy does in blackjack. The decision points in roulette are which bets to place and how much to stake, not how to play a hand. What a strategy discussion can do is show you which bets carry the lowest house edge on the wheel in front of you, and which bets accelerate your expected loss. On a European wheel, the even-money outside bets and the inside bets share the same standard edge in most rule sets, so the choice is about volatility rather than edge. A straight-up number pays more but hits far less often; red or black pays even money but hits close to half the time, excluding the zero.
If you are looking at a strategy chart for any table game, the first line of the chart should tell you which rule set it assumes. In blackjack, basic strategy derives from the specific rule set in use: the number of decks, whether the dealer stands or hits on soft 17, and which doubling and splitting rules apply. A chart built for one rule set can be wrong for another. The same discipline applies to roulette: a house-edge figure quoted for a European wheel does not transfer to an American one, and a rule like en prison changes the edge on even-money bets only.
Procedural mistakes that cost new players
The first mistake is sitting down without checking which wheel is in front of you. If you assume a European wheel and the table has a double zero, every bet you place carries a higher house edge than the figure you may have read. The second mistake is treating the zero as a push on outside bets. It is not. On a standard layout, zero is a losing pocket for red, black, odd, even, high and low, and on an American wheel there are two such pockets. The third mistake is betting after the dealer has called no more bets. A late chip is returned to you or, if it interferes with the spin, may be ruled void, and repeated late betting will draw the attention of the pit staff. The fourth is walking away from the table with roulette chips still in your hand. They have no value at the cashier; they must be coloured up at the table where they were issued.
FAQ
Why does the American wheel have an extra pocket?
The double zero was added to the American layout as a second house pocket. It increases the house edge on most bets because the payout schedule remains the same while the probability of any given bet winning falls from 1 in 37 to 1 in 38 on a single-number bet, and the even-money bets gain a second losing green pocket.
Does the zero ever pay out on a roulette wheel?
You can bet on the zero directly as a straight-up number, and it pays 35 to 1 when it hits, just like any other single number. On an American wheel, the single zero and the double zero are separate bets. On outside bets such as red or black, the zero pockets are neither red nor black and lose on a standard layout.
How do I know which wheel a table is using before I play?
Look at the wheel itself or the table layout. A European wheel shows one green zero pocket, and an American wheel shows both a single zero and a double zero, usually marked 0 and 00. The layout will also show the double zero as a betting space if the table uses an American wheel. If you are unsure, ask the dealer before you place a bet.
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This article is general information about how these mechanics work. It is not legal advice and not a recommendation to gamble or to use any particular operator. Availability and legality differ by jurisdiction — check the rules that apply where you are.