The extra pocket changes every bet you make
You are looking at two roulette layouts that look almost identical, and the only visible difference is a second green pocket marked 00. That single pocket is not a cosmetic detail. It changes the arithmetic of every wager on the table, because the wheel now has one more losing number for most bets while the payouts stay the same.
A European wheel has 37 pockets: the numbers 0 through 36, with a single green zero. An American wheel has 38 pockets: the same 0 through 36 plus a green 00. When you bet on a single number, the European layout pays 35 to 1, and the American layout also pays 35 to 1. But on the European wheel your number is one of 37, while on the American wheel it is one of 38. The payout did not grow to match the extra pocket, so the operator's mathematical advantage grows instead.
This is why players who compare the two layouts usually prefer the single-zero wheel. It is not about the zero itself doing anything special. It is about how many total pockets the payout has to cover.
What the zero and double zero do
The green pockets are not player numbers. On most roulette bets, neither the 0 nor the 00 counts as a win. If you bet on red or black, on odd or even, or on high or low, a green pocket lands outside all of those categories, so the bet loses. The zero pockets are also not covered by column or dozen bets in the usual layout.
That is the mechanical role of the zero: it is the pocket that sits outside the even-money and grouping bets, which is precisely where the house edge on those bets comes from. On a European wheel, an even-money bet covers 18 of the 37 pockets. On an American wheel, the same bet covers 18 of 38. The payout is 1 to 1 either way, but the proportion of winning pockets has fallen.
Some tables offer a rule variation called la partage or en prison on even-money bets, most often on single-zero layouts. Under those rules, a losing even-money bet that lands on zero may be returned in part or held for the next spin rather than collected in full. That rule reduces the edge on those specific bets, but it is a table rule, not a property of the wheel itself, and it does not apply to every game.
How the two wheels compare
The cleanest way to see the difference is to put the two layouts side by side for the same bet. The table below uses the allowed constants for roulette wheels and shows how the same wager behaves on each layout under standard rules.
| Feature | Single-zero wheel (European) | Double-zero wheel (American) |
|---|---|---|
| Total pockets | 37 | 38 |
| Green pockets | One (0) | Two (0 and 00) |
| Winning pockets on an even-money bet | 18 of 37 | 18 of 38 |
| Payout on a single-number bet | 35 to 1 | 35 to 1 |
| Effect of the extra pocket | Not present | Raises the house edge on most bets |
The table does not attach a percentage to either wheel because the exact house edge depends on the bet type and on any table rule variations. What stays true across both layouts is that the double-zero wheel gives the operator a wider margin on the same bet, because the payout schedule has not been adjusted for the additional pocket.
Which bets carry the widest gaps
Not every bet is affected equally by the second zero, but every bet is affected. A straight-up bet on a single number loses one additional way on the American wheel. An even-money bet loses one additional way. A split, street, corner and six-line bet all lose one additional way. The pattern is uniform: the payout table stays fixed while the denominator of the wheel grows from 37 to 38.
The bet types themselves are worth understanding before you sit down, because their edges differ materially even on the same wheel. The table below summarises the main categories as they appear on a standard layout.
| Bet type | What it covers | Payout | How the zeros affect it |
|---|---|---|---|
| Straight up | One number | 35 to 1 | Loses on either zero |
| Split | Two adjacent numbers | 17 to 1 | Loses on either zero |
| Street | Three numbers in a row | 11 to 1 | Loses on either zero |
| Corner | Four numbers meeting at a corner | 8 to 1 | Loses on either zero |
| Six line | Six numbers in two rows | 5 to 1 | Loses on either zero |
| Dozen or column | Twelve numbers | 2 to 1 | Loses on either zero |
| Even-money | Red, black, odd, even, high, low | 1 to 1 | Loses on either zero unless a la partage or en prison rule applies |
On a double-zero wheel, every row in that table has one more losing pocket than it does on a single-zero wheel. The payout column never changes. That is the entire difference in a sentence: same payouts, one more losing pocket.
Reading the table before you buy in
When you approach a roulette table, the wheel type is the first thing to identify, and it is usually visible before you sit down. The wheel itself shows whether it carries a 00. The layout printed on the felt also shows it, because the betting area includes a 00 box next to the 0. If you are playing an electronic or live-dealer roulette game, the same information appears on the game screen or in the game rules panel.
The table rules should also state whether any special rule applies to even-money bets when a zero lands. That rule can change the edge on those bets, so it matters more than the colour of the felt or the name of the game. If the rule is not printed on the layout, the dealer or the game information panel is the source to ask.
One procedural mistake new players make is assuming that all roulette tables are the same game with different decoration. They are not. The wheel configuration is a rule of the game, not a style choice, and it changes the expected rate of loss on every spin. A second mistake is placing bets before understanding which bets the zeros defeat. Even-money bets feel safe because they win almost half the time, but on a double-zero wheel they lose more often than the payout suggests. A third mistake is chasing a number or colour that has appeared recently. Each spin is an independent event on a properly functioning wheel; the previous spin does not change the number of pockets on the next one.
Where the wheel type is stated
If you are comparing two roulette games and cannot see the wheel clearly, the game information or help panel is the place to look. It will state the wheel configuration, the bet limits, and any special rules such as la partage or en prison. The operator's game rules page carries the same information for online play. The house edge for a specific bet is not always printed on the layout, but the wheel type plus the payout table is enough to understand why one layout is more expensive to play than the other.
Roulette is a negative-expectation game on both wheel types. No bet selection changes that. What the player controls is which wheel they sit at, which bets they place, how many spins they play, and how much they stake per spin. Those choices determine the rate at which the edge is applied, not whether the edge exists.
FAQ
Is the double zero just another zero, or does it work differently?
It works the same way as the single zero. It is a green pocket that sits outside the usual betting categories, so most bets lose when it lands. The difference is that it adds one more pocket to the wheel without changing any payout, which widens the operator's margin on every bet.
Why do some roulette games have one zero and others have two?
The single-zero layout is the older European configuration. The double-zero layout adds a second green pocket, which increases the house edge. Which layout a given table uses is a rule of that table, not a universal standard, so it is always worth checking before you play.
Does the zero affect every roulette bet equally?
It affects every bet in the same direction, because every bet loses on a zero unless a special rule applies. But the size of the effect differs by bet type, because the payout and the number of covered pockets vary. Even-money bets are particularly sensitive to the number of green pockets, since they cover only 18 numbers either way.
Gambling involves risk. Please only gamble with funds that you can comfortably afford to lose. While we do our best to provide good quality information, we cannot guarantee the accuracy or completeness of any information presented. Gambling can be addictive; please play responsibly. If you or someone you know is struggling with gambling addiction, seek help from a professional organisation such as Gamblers Anonymous or a national helpline. This content is for informational purposes only and does not constitute legal, financial, or professional advice.
Play responsibly
Gambling should be treated as paid entertainment, never as a way to earn income or recover losses. 1-800-MY-RESET (1-800-697-3738)
18+ or 21+ depending on where you are; follow the minimum age that applies to you.
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.