European vs American Roulette: rules, differences and impact on expected value

Roulette looks simple on the surface, but small rule changes can double the long-term cost of play. The key difference between European and American roulette is the number of zero pockets on the wheel, and that single detail changes the probabilities behind every bet. In this guide, I’ll break down the rules, layouts and payouts, then connect them to expected value so you can understand what you are paying for with every spin in 2026.

Wheel and table rules: what actually changes between the two games

European roulette uses a wheel with 37 pockets: numbers 1 to 36 plus a single zero (0). American roulette adds an extra pocket, the double zero (00), bringing the total to 38. Payouts for standard bets are usually the same in both games, so the extra pocket mainly works as a silent probability shift in the casino’s favour.

That difference also appears on the table layout. European tables typically show a single zero area, while American layouts include both 0 and 00, and many American tables also print additional “top” or “basket” bet markings. Those markings are not just decoration: they often indicate side bets that create higher volatility and, in many cases, a higher house edge than ordinary inside/outside wagers.

Another practical difference is availability of special even-money rules. On many European tables—especially those marketed as “French roulette”—you may see La Partage or En Prison applied to even-money bets (red/black, odd/even, high/low). These rules reduce losses when the ball lands on zero, but they are not automatically present in every European game, and they are rarely offered on standard American roulette.

How many numbers you cover, and why that matters more than most players think

Every roulette bet is a trade: you exchange a chance at a payout for a probability of losing your stake. When you add an extra pocket to the wheel, you dilute the probability of hitting any particular outcome—straight numbers, dozens, columns, colours, everything—because the payouts do not increase to compensate. That is why the “feel” of the game may look identical, while the maths underneath becomes less forgiving.

For example, a straight-up bet pays 35:1 in both variants. In European roulette you win that bet 1 time out of 37, while in American roulette you win 1 time out of 38. That sounds like a tiny change, but over hundreds or thousands of spins it becomes measurable money, because the rare win is what offsets the frequent losses—and the offset is weaker when the hit rate drops.

Outside bets show the same pattern. Red/black covers 18 numbers; in European roulette that’s 18/37, while in American roulette it’s 18/38. The extra 00 does not add any winning outcomes for those bets, so it functions like an additional “dead” pocket for many common wagers, increasing the average loss per unit staked.

House edge, RTP and expected value: the numbers behind the difference

If payouts are unchanged, the extra pocket translates directly into a bigger house edge. In European roulette with one zero, the house edge is 1/37, which is about 2.70%, meaning the theoretical return-to-player (RTP) is about 97.30% over the long run. In American roulette with 0 and 00, the house edge is 2/38, about 5.26%, so the RTP is about 94.74%.

Expected value (EV) is the cleanest way to interpret that. If you stake £10 per spin on bets with the standard house edge, the average theoretical loss is about £0.27 per spin in European roulette (2.70% of £10) and about £0.53 per spin in American roulette (5.26% of £10). Real sessions will swing above and below that average, but the longer you play, the more the results tend to drift toward the expectation.

Special even-money rules can change the EV meaningfully. With La Partage (typically: half your even-money stake is returned when zero hits), the house edge on even-money bets in a single-zero game effectively halves to about 1.35%. En Prison produces a similar long-run effect for even-money wagers, although it plays out through a “stake held” mechanic rather than an immediate half refund.

Worked examples: how the extra zero changes the maths of common bets

Take an even-money bet, say £10 on red. In European roulette (single zero, no special rule), the probability of winning is 18/37 and losing is 19/37 (because zero is a loss), with a net win of £10 on a hit and a net loss of £10 otherwise. The EV is (18/37 × £10) + (19/37 × -£10) = -£10/37 ≈ -£0.27 per spin.

Now the same bet in American roulette: win probability is 18/38 and loss probability is 20/38 (0 and 00 both lose). EV becomes (18/38 × £10) + (20/38 × -£10) = -£20/38 ≈ -£0.53 per spin. The stake and payout are identical, but the extra losing pocket makes the average loss almost exactly double.

With La Partage on a European even-money bet, zero no longer costs the full stake. Using the same £10 on red, you win £10 with probability 18/37, lose £10 with probability 18/37 (the opposite colour), and lose £5 with probability 1/37 (zero). EV becomes (18/37 × £10) + (18/37 × -£10) + (1/37 × -£5) = -£5/37 ≈ -£0.14 per spin, which corresponds to the 1.35% house edge on that class of bet.

Volatility, bankroll impact and why “systems” don’t change expectation

Roulette is a negative-expectation game in standard casino conditions, and the edge is built into the wheel and payouts. That means betting systems cannot turn a losing expectation into a winning one; they can only change how your results are distributed over time. In plain terms: you can choose to lose slowly with low variance or risk sharper swings with higher variance, but the long-run average still tracks the house edge.

Progression systems such as Martingale feel persuasive because they produce many small wins in calm stretches. The cost is that they also create rare but very large losses when a streak runs longer than your bankroll—or when table limits stop you from continuing to double. In 2026, table limits remain one of the most practical “hidden rules” because they cap how far any progression can go, regardless of how confident the maths looks on paper.

American roulette’s higher edge changes bankroll pressure even when volatility is the same. If you play long sessions with the same average stake size, the higher expected loss means your bankroll needs to be larger simply to sustain the same amount of play time. Put another way: the extra 00 does not just change theory, it changes how quickly a typical bankroll is likely to erode.

How to make a smarter game choice in practice, before you place a bet

First, identify the variant: single-zero (European) vs double-zero (American). In physical venues, you can usually confirm this by looking at the wheel or the felt. In online lobbies, it is often shown in the game name, but it is still worth checking the rules panel because marketing labels are not always consistent, especially when side bets and special rules are involved.

Second, check whether La Partage or En Prison applies, and to which bets. Some games apply it only to even-money bets; others may not offer it at all. If your style of play leans heavily on red/black, odd/even, or high/low, the presence of La Partage can reduce the theoretical cost of play substantially compared with both standard European rules and any double-zero table.

Finally, manage risk like it matters: set a budget you can comfortably afford to lose, decide in advance what ends the session (time, loss limit, or win limit), and treat roulette as paid entertainment rather than an income plan. If gambling ever stops feeling controlled—chasing losses, hiding spend, or playing beyond your means—pause and seek help through local support services in your country.