European vs. American Roulette: Why One Green Zero Changes Everything
The answer sits in a single pocket.
The answer sits in a single pocket. European roulette carries a 37-pocket wheel (numbers 1 through 36 plus one green zero) and a house edge of 2.70% on nearly every wager, about 2.7 ENT per 100 staked. American roulette adds a second green pocket, the 00, for 38 pockets total, which pushes the house edge to 5.26% on almost all bets (about 5.26 ENT per 100 staked) and to 7.89% on the five-number bet covering 0, 00, 1, 2, and 3. Nothing else changes: the numbers, the layout, the payouts, and the betting structure are identical between the two wheels. The single extra losing pocket on the American wheel is the entire difference, and it happens to nearly double the house's long-run take. This is not a matter of superstition or 'hot' tables; it is arithmetic. A straight-up bet pays 35 to 1 regardless of which wheel is spinning, but the true odds shift from 36 to 1 on the European wheel to 37 to 1 on the American one. That widening gap between true odds and posted payout is where the edge lives. For anyone weighing the two games side by side, the practical guidance is simple and unambiguous: given a choice, the single-zero wheel costs roughly half as much per unit staked over time.
What is the fundamental difference between European and American roulette?
The European wheel carries 37 pockets (1 through 36 plus a single 0), while the American wheel carries 38 pockets (1 through 36 plus 0 and 00). Every rule, bet, and payout is otherwise identical; the American wheel simply adds one additional losing pocket for the house.
Beyond the pocket count, the two wheels look nearly identical at a glance: the same red and black numbering, the same betting layout of inside straight-up and split wagers alongside outside red/black, odd/even, and dozens wagers, and the same payout table. That similarity is precisely why the distinction matters. A player who does not know to look for the second green pocket can sit down at an American table believing the odds mirror the European game next to it, when in fact the house's structural advantage has nearly doubled simply by virtue of which wheel is on the table.
One extra pocket. Nearly double the house edge.
Why does one extra pocket nearly double the house edge?
The house edge is set by how many losing numbers exist relative to the payout offered. Adding the 00 pocket does not change any payout; it only adds one more way to lose. That single change moves the edge from 2.70% to 5.26%, which is almost exactly double.
On the five-number bet unique to the American wheel (0, 00, 1, 2, 3), the effect is even sharper: the house edge climbs to 7.89%, the worst wager on either wheel. This bet exists only because the American layout groups the two zeros with three low numbers into one wagering option; the European wheel, lacking a second zero, has no equivalent bet. Everywhere else on the table, the extra pocket applies its drag uniformly, since every other bet's payout was set for a 37-pocket wheel and simply was not adjusted when the second zero was added.
How is the house edge actually calculated from the payout odds?
Every roulette bet's edge comes from the gap between true odds and the posted payout. A straight-up bet pays 35 to 1, but the true odds are 36 to 1 on a European wheel and 37 to 1 on an American wheel; that gap is the house edge, expressed as a percentage.
Consider the arithmetic plainly: on a 37-pocket wheel, a single number should, over many spins, win once in 37 tries. A fair payout for that probability would be 36 to 1. The casino pays 35 to 1 instead, keeping the difference. On the 38-pocket American wheel, the same number wins once in 38 tries on average, so fairness would require 37 to 1, yet the payout remains 35 to 1. The house's built-in margin against fair odds is what produces 2.70% on the European wheel and 5.26% on the American wheel, and this ratio holds across inside and outside bets alike.
What are la partage and en prison, and how much do they change the math?
Both rules apply only to even-money bets (red/black, odd/even, high/low) on wheels that offer them, typically European tables. Under la partage, a 0 spin returns half the stake to the player. Under en prison, the stake is held for the next spin. Either rule roughly halves the edge on those bets to about 1.35%.
These rules do not exist on the American wheel and are not universal even in Europe; they are table-specific concessions, most common at premium single-zero tables. Where offered, they change the outcome only for the narrow set of even-money wagers, leaving every other bet, the straight-up numbers, the splits, the columns, the dozens, at the full 2.70% European edge. A player choosing a table should confirm whether la partage or en prison is posted, since its presence on an already favorable single-zero wheel is the single best structural condition available in roulette.
La partage roughly halves the edge on even-money bets alone.
Does the house edge really apply equally to every bet on the table?
Yes, with one exception. On both wheels, virtually every bet, inside or outside, carries the same house edge (2.70% European, 5.26% American) because the payout-to-true-odds gap is constant. The lone outlier is the American five-number bet, which carries a steeper 7.89% edge.
This uniformity surprises many players, who assume that a single straight-up number is somehow 'riskier' than a red/black wager, or that column bets offer better value than dozens. In pure house-edge terms they do not; the casino's percentage take is the same whether the stake sits on one number or spreads across eighteen. What differs between bets is volatility, how large and how rare the winning payout is, not the long-run edge itself. That distinction matters for anyone comparing wagers, since the edge is fixed regardless of which bet carries the money.
Do betting systems, or a run of past results, change the odds?
No. Roulette has no memory; every spin is an independent event, so a run of reds or a 'cold' number has no bearing on the next outcome. Betting systems such as Martingale rearrange wager sizes but never alter the built-in house edge or bypass table limits.
On a single-zero wheel, red and black each occupy 18 of 37 pockets, close to 48.6% of outcomes; the remaining 2.7% belongs to the zero, and that sliver is precisely where the edge on even-money bets resides absent la partage. No sequence of spins shifts that split, because the wheel and ball carry no record of prior results. A system like Martingale, doubling the stake after a loss, can win back a deficit in the short run, but it does so by escalating exposure toward the table's betting limit, and the underlying probability of each spin never moves.
The house always knows this
Single-zero wheels cost about half as much as double-zero wheels; the edge is fixed and no system changes it.
Frequently asked
If I can choose either wheel, which one should I play?
Always prefer the single-zero European wheel when available. Its house edge of 2.70% is roughly half the American wheel's 5.26%, meaning the double zero costs a player about twice as much per unit staked over time. The bets and payouts are otherwise identical, so the choice costs nothing to make.
Is the house edge really the same on every bet, inside and outside?
On each wheel, yes, with one exception. Every standard inside and outside bet carries the same 2.70% (European) or 5.26% (American) edge. The sole exception is the American five-number bet (0, 00, 1, 2, 3), which carries a higher 7.89% edge because of how its payout was set.
Does a number that hasn't hit in a while become 'due'?
No. Roulette has no memory. Each spin is a fully independent event, so a number's recent absence, or a long run of one color, carries zero predictive weight for the next result. The probability of any number or color appearing stays exactly the same on every single spin.
What exactly does la partage mean for a player at the table?
La partage applies only to even-money bets on wheels that offer it. If the ball lands on 0, the player recovers half the original stake instead of losing it all. That single concession lowers the edge on those bets from 2.70% to about 1.35%, the best odds available anywhere in roulette.
Why does adding just one pocket nearly double the house's advantage?
Because the payout structure never adjusts for it. A straight-up number still pays 35 to 1 on both wheels, but true odds move from 36 to 1 to 37 to 1 with the extra pocket. That widened gap between fair odds and the fixed payout is what nearly doubles the edge, from 2.70% to 5.26%.
Sources & further reading
ENTBlog is educational. Every casino game carries a house edge, so the mathematically expected result of play is a net loss over time. Play for entertainment, within limits you set in advance. Nothing here is financial advice or a promise of winnings.