American roulette has both 0 and 00 because the second green pocket gives the casino an additional winning outcome without increasing the standard payouts offered to players.
The effect is not limited to bets placed near zero on the layout. It changes the price of every ordinary roulette wager.
What the two green pockets actually do
A double-zero wheel contains 38 pockets:
- 18 red numbers;
- 18 black numbers;
- one green 0;
- one green 00.
Traditional straight-up roulette pays 35 to 1 even though a winning number is only one of 38 possible pockets.
That mismatch—35-to-1 payout on a 38-outcome wheel—is the source of the standard 5.26% house edge.
Zero and double zero are valid winning numbers for wagers that include them. But for red/black, odd/even, high/low, dozens, columns, and most number combinations that do not cover them, either green pocket is a losing result.
The second zero nearly doubles the house edge
The cleanest comparison uses a $1 straight-up bet on one number.
Single-zero wheel
A single-zero wheel has 37 pockets. The player wins $35 on one result and loses $1 on the other 36:
[ EV = \left(\frac{1}{37} \times 35\right) - \left(\frac{36}{37} \times 1\right) ]
[ EV = -\frac{1}{37} \approx -$0.0270 ]
The expected loss is about 2.70 cents per $1 wagered, so the house edge is approximately 2.70%.
Double-zero wheel
A double-zero wheel has 38 pockets. The payout is still 35 to 1, but there are now 37 losing pockets:
[ EV = \left(\frac{1}{38} \times 35\right) - \left(\frac{37}{38} \times 1\right) ]
[ EV = -\frac{2}{38} \approx -$0.0526 ]
The expected loss is about 5.26 cents per $1 wagered, giving a 5.26% house edge.
The extra zero does not exactly double the edge, but it comes close: 5.26% versus 2.70%.
Even-money bets are affected in the same way
Red looks like half the wheel because 18 numbers are red and 18 are black. The green pockets prevent it from being a true 50-50 wager.
On a double-zero wheel, a $1 red bet has:
- 18 winning pockets;
- 20 losing pockets: 18 black, 0, and 00.
The expected value is:
[ EV = \left(\frac{18}{38} \times 1\right) - \left(\frac{20}{38} \times 1\right) = -\frac{2}{38} ]
That is the same 5.26% house edge as a standard straight-up bet. The payout and hit frequency differ, but the underlying edge is the same for ordinary bets on the same wheel.
This is why changing from a number bet to red/black reduces volatility but does not remove the double-zero disadvantage.
Why roulette developed into single- and double-zero versions
The history is more interesting than “American casinos added 00.” Early documented roulette games already used both zero and double zero. In the 1840s, François and Louis Blanc promoted a single-zero wheel in Bad Homburg by removing the double-zero pocket, offering a more favourable game than competing double-zero tables.
European casinos largely adopted the single-zero form. The older double-zero form remained established in the United States and became known as American roulette. A historical roulette in the Belgian National Lottery Museum notes both the earlier two-zero form and the later American retention of double zero.
The modern labels therefore describe regional traditions, not two games invented independently from the beginning.
For a player today, the practical history is simple: single-zero roulette competes by offering a lower mathematical price, while double-zero roulette earns more expected revenue from the same amount of standard action.
The payouts did not expand with the wheel
A fair 38-pocket straight-up payout would need to return 37 units of profit for a 1-unit wager. Standard roulette pays 35 to 1.
The difference is easy to miss because “35 to 1” sounds large. It is large relative to the stake, but still smaller than the fair payout required by the probability.
| Wheel | Pockets | Fair straight-up profit odds | Standard profit payout | Standard house edge |
|---|---|---|---|---|
| Single zero | 37 | 36 to 1 | 35 to 1 | 2.70% |
| Double zero | 38 | 37 to 1 | 35 to 1 | 5.26% |
| Triple zero | 39 | 38 to 1 | 35 to 1 | 7.69% |
For a present-day rules reference, the Nevada Gaming Control Board’s double-zero roulette rules specify 38 equally possible pockets. For historical context, the Belgian National Lottery Museum’s roulette collection entry describes the transition from the older two-zero form to the single-zero version and the American retention of 00.
Triple-zero roulette extends the same mechanism. A third green pocket is added while standard payouts usually remain unchanged. Players should identify the actual wheel rather than assume that every roulette table has the familiar 37 or 38 pockets.
Does 00 have a special probability?
No. On a balanced double-zero wheel, 00 is one pocket among 38. It is not more likely because it is written with two characters, placed at the top of the layout, or associated with a particular table section.
A straight-up bet on 00 has the same one-in-38 hit probability as a straight-up bet on 17. A split or basket wager that includes 00 follows the probability and payout rules printed for that combination.
The visual layout is not the wheel order. Numbers that appear next to one another on the betting cloth may be far apart on the physical wheel.
Rules such as la partage can change only part of the comparison
Some single-zero games apply la partage or en prison to even-money wagers when zero appears. Under la partage, for example, the player may lose only half of an even-money stake when the ball lands on zero. That can reduce the house edge on qualifying bets to about 1.35%.
Those rules do not automatically apply to every single-zero table, and they generally do not improve inside bets. The table’s posted rules matter as much as the number of zeros.
Read En Prison and La Partage for the rule-specific details.
What to check before placing a chip
A roulette player can identify the main price difference in a few seconds:
- Count the green pockets on the wheel or layout.
- Check whether the game uses standard or altered payouts.
- Look for la partage or en prison on single-zero even-money bets.
- Avoid assuming an electronic or multiplier version follows the traditional paytable.
- Compare the total cost, not just the table minimum.
A $10 minimum on a 5.26% wheel is not automatically cheaper than a $15 minimum on a 2.70% wheel. Session length, spin rate, and total amount wagered determine the expected dollar cost.
The second zero is not a harmless design detail. It is one additional losing outcome built into the same familiar payouts.
Continue with
Use Roulette Wheel Differences for wheel layouts and rule variants, Roulette for the complete game guide, and the Roulette Bet Comparison Tool to compare probability, payout, and house edge across wagers.