At first glance, roulette is the same everywhere. The wheel, the ball, the red and black numbers. In Worcester, you can come across it even without a trip to a large casino – for example, on slot machines in betting shops.
For Category B2 FOBTs (Fixed-Odds Betting Terminals), which can be installed in such venues, British legislation stipulates a maximum stake of £2 per game and a maximum win of £500 per spin. However, the specific selection of games on the machine is determined by the operator, not the customer.
Online, the choice is wider. Three classic roulette variants might be available side by side: European, American and French.
They look almost identical, but mathematically they are different games. In the most common variants, the house edge ranges from 1.35 percent (for even-money bets under certain rules) to 5.26 percent.
None of these figures is a secret: review platforms publish the rules and house edge for each version, and readers can find all about gambling on Slotozilla, from roulette guides to casino and bonus reviews. Still, a percentage on a review page only makes sense once you know where it comes from. And the answer is visible on the wheel itself: count the green pockets.
One extra zero: why American roulette is more expensive for the player
In classic European roulette, the wheel has 37 sectors: numbers from 1 to 36 and one green zero.
In the American version, there are 38 sectors. A double zero – 00 – is added to the usual zero.
It might seem like a minor difference – just one extra sector on the large wheel. But it is precisely this that significantly alters the mathematical odds.
Let’s take the simplest bet – on red. In both versions, there are 18 red and 18 black sectors. The payout for a win is 1:1. If you bet £2 and guess the colour correctly, your net winnings will be £2, and your original stake will be returned.
However, the probability of winning differs. In European roulette, red comes up in 18 out of 37 possible outcomes, i.e. approximately 48.65 percent. In American roulette, it comes up 18 times out of 38, or 47.37 percent. The payout remains the same, but the probability of winning has decreased.
This is why the house edge in European roulette is 2.70 percent, whilst in American roulette it is 5.26 percent. On review websites, these same figures are usually presented as RTP, i.e. the proportion of stakes that the game returns on average: 97.30 percent for European, 94.74 percent for American and 98.65 percent for French – for even-money bets under special rules, which are discussed below.
The additional zero does not simply increase the number of sectors. It doubles the number of green outcomes on which standard bets on red or black lose, even though the total number of sectors increases by only one.
And this applies not only to colours. On the American wheel, the house edge of 5.26 percent applies to all standard bets: on individual numbers, dozens and combinations. The exception is the bet on five numbers (0, 00, 1, 2, 3): here the house edge reaches 7.89 percent, making it the worst bet on the table.
French roulette: the same wheel, but different rules
Whilst the American version shows what an extra zero does to a player’s odds, the French version demonstrates the opposite: what happens when the effects of the zero are mitigated by the rules. The wheel here is the same as in the European version – the only difference lies in how the table handles the bet when the ball lands on the green sector.
The third variant, French roulette, looks almost identical to the European version. The same 37 sectors, a single zero, 18 red and 18 black numbers. Even the mathematical probability of a specific number coming up remains the same.
However, there is one important difference: what happens to the bet when the ball lands on zero.
In French roulette, the special rules known as La Partage or En Prison may apply. Usually, a particular table uses one of these, rather than both at the same time.
La Partage: half the bet is returned
Let’s imagine that a player has bet £2 on red, but the ball lands on zero.
In standard European roulette, the entire stake would be lost.
Under the La Partage rule, half the stake is returned to the player if they have bet on even-money outcomes – red/black, even/odd or 1–18/19–36. The remaining £1 stays with the house.
This is neither a bonus nor an additional win. It is simply a partial refund of the stake in the event of a specific outcome.
But it is precisely this rule that halves the house’s mathematical advantage – from 2.70% to 1.35%.
En Prison: the stake remains until the next spin
The En Prison rule works differently. If zero comes up, a bet placed on even money does not lose immediately, but remains on the table until the next spin.
Suppose a player has bet £2 on red. Zero comes up, and the bet goes ‘to prison’: it is held on the table until the next spin.
If red comes up next time, the player simply gets their £2 back – with no profit. If black comes up, the bet is lost. The rules regarding a second zero may vary depending on the table.
The house edge for En Prison is approximately 1.35–1.39%, depending on what happens in the event of a second zero. In the common single-zero version, where a repeat zero results in a loss, it is closer to 1.39%.
La Partage and En Prison apply only to even-money bets: red or black, even or odd, numbers 1 to 18 or 19 to 36.
If you bet on a single specific number, these rules won’t help. For such a bet, the house edge in French roulette remains at 2.70 percent, just as it does in European roulette.
Therefore, the label ‘French roulette’ does not in itself mean that all bets have a house edge of 1.35 percent. You need to check the specific rules of the table.
What do these percentages mean in real-money terms?
The house edge is a mathematical expectation that describes the average proportion of losses relative to the total amount staked over a very long period.
Let’s imagine a player from Worcester who has placed £1,000 in bets over a few evenings playing online roulette. This isn’t necessarily £1,000 of their own money: the same balance can be used across many spins.
Under standard rules, the theoretical expected losses would be as follows: with a house edge of 1.35 percent (French roulette with La Partage, even-money bets), the statistical loss from £1,000 could be £13.50; at 2.7 percent (European roulette, as well as French roulette for other bets) – £27; at 5.26 percent (American) – £52.60. These are statistical figures, not amounts that a specific person is bound to lose.
In a single hour, you can win or lose considerably more. The results of individual spins remain random, and previous numbers do not influence subsequent ones.
However, over the long term, the mathematical difference between the versions becomes significant. American roulette has almost twice the house edge of European roulette, and almost four times that of French roulette with its special rules for even-money bets.
Bonuses: another set of rules that’s easy to overlook
Aside from the wheel itself, the terms of play may be influenced by a bonus offer.
For example, a promotion may apply only to live dealer roulette, but not to the computerised version using a random number generator (RNG). Or, conversely, it may only allow certain digital tables.
That is why it pays to compare offers before claiming one. For players in the UK, Slotozilla brings together no-deposit rewards for roulette on a single page, listing each offer’s validity, wagering requirement, maximum stake and eligible tables. The line that matters most, however, is often the smallest: wagering contribution.
Different games contribute differently towards meeting bonus conditions, and table games often count for significantly less than slots.
From 19 January 2026, the Gambling Commission has capped wagering requirements at ten times the bonus amount. However, this limit does not remove the game contribution rates. If slots count towards the wagering requirement in full, whilst roulette – say – counts for only 10 percent (a £1 bet reduces the requirement by 10 pence), then a £10 bonus with a 10x requirement means £100 in bets on slots and £1,000 on roulette. This does not mean that your balance must be £1,000: the same money is used across multiple bets. However, no one can guarantee that you will be able to wager such an amount without incurring losses.
The reason for these restrictions is clear: table games with a relatively small house edge often have different bonus terms to slots.
It is therefore important to check not only the size of the advertised bonus, but also whether a specific version of roulette is permitted and how bets are counted.
For users in England, Scotland and Wales – that is, wherever the Gambling Commission’s regulations apply – it is important to ensure that the operator holds a licence from the Commission. The mere presence of an offer on an information website does not in itself confirm its availability or legality for a specific user.
A difference you can spot even before the first spin
Three versions of roulette may appear side by side in a single online catalogue. Their names differ only in terms of geography, whilst the gameplay itself looks almost identical. However, one extra green pocket increases the house edge. And one special rule regarding the zero can reduce it for certain bets.
This is a case where a minor detail in the rules matters more than the layout of the table or the name of the game.
Before starting a game of roulette, it’s worth checking three things: how many zeros are on the wheel, whether La Partage or En Prison applies, and what limits are set for that particular table. None of these details allows you to predict the next number. But they all determine the mathematical odds that the player is agreeing to.
And unlike the outcome of a spin, these conditions can be known in advance – whether it’s an online table or a terminal at a bookmaker’s on the high street in Worcester.
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