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On this page
- Casino offers we list
- The wheel and the bets
- Worked maths: European roulette (single zero)
- Worked maths: American roulette (double zero)
- La partage and en prison
- What the edge means in pounds
- Why roulette systems don’t work
- Roulette and casino bonuses
- UK rules that apply
- Staying in control
- Frequently asked questions
- Sources checked
- More from our casino section
Roulette house edge comes straight from the wheel: European roulette has 37 pockets (1–36 plus a single zero) but pays as if there were 36, giving a 2.70% edge on every standard bet. American roulette adds a double zero, raising it to 5.26%. Tables using “la partage” or “en prison” halve the edge on even-money bets to 1.35%. Here’s the maths worked through, and why no system changes it.
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The wheel and the bets
Roulette bets split into inside bets (single numbers or small groups) and outside bets (red/black, odd/even, 1–18/19–36, dozens and columns). The zero is neither red nor black, odd nor even, so outside bets lose when it lands (unless a special rule applies).
Worked maths: European roulette (single zero)
Straight-up bet (one number), pays 35:1. There is 1 winning pocket and 36 losing ones.
Expected value per £1 = (1 × £35 − 36 × £1) ÷ 37 = −£1 ÷ 37 ≈ −2.70%
Red or black, pays 1:1. There are 18 winning pockets and 19 losing ones (18 of the other colour plus zero).
Expected value per £1 = (18 − 19) ÷ 37 = −£1 ÷ 37 ≈ −2.70%
The same −1/37 result applies to dozens (12 numbers, pays 2:1: (12 × 2 − 25) ÷ 37) and every other standard bet. Bet choice changes how often you win and how much, not the edge.
Worked maths: American roulette (double zero)
With 0 and 00, there are 38 pockets but the same payouts.
Straight up: (35 − 37) ÷ 38 = −2 ÷ 38 ≈ −5.26%
The “top line” or five-number bet (0, 00, 1, 2, 3) pays 6:1: (5 × 6 − 33) ÷ 38 = −3 ÷ 38 ≈ −7.89%, the worst bet on the table. If you have a choice, a single-zero wheel roughly halves the edge.
La partage and en prison
Some French-rules tables return half your stake on even-money bets when zero lands (la partage), or hold the stake for the next spin (en prison). With la partage, the loss on zero is halved, so the even-money edge becomes:
(18 − 18 − 0.5) ÷ 37 = −0.5 ÷ 37 ≈ −1.35%
This only applies to even-money bets; inside bets stay at 2.70%. Check the game’s help screen: online and live roulette games state their rules and RTP there (for example, 97.30% RTP corresponds to a 2.70% edge).
What the edge means in pounds
Expected loss = house edge × total staked. If you place 100 spins of £1 on European roulette, you’ve staked £100 and the expected loss is about £2.70. On an American wheel, it’s about £5.26. Over a short session the actual result will vary widely; over long play, results drift towards these figures. Because roulette spins are fast online, total amount staked can climb quickly even with small stakes.
Why roulette systems don’t work
Every spin is independent: the wheel has no memory, so a run of reds doesn’t make black “due”. Systems like Martingale (double after a loss), D’Alembert or Fibonacci only rearrange stakes. Since every bet has the same −2.70% expectation on a single-zero wheel, any combination of bets still has −2.70% expectation of the total staked. Progressive systems also hit table maximums or your budget after a losing run, turning many small wins into one large loss.
Roulette and casino bonuses
Roulette often counts less towards bonus wagering, or is excluded. Unibet’s verified free spins offer says table games contribute 10% to wagering, and 10bet’s bonus must be wagered on slots. The Gambling Commission’s guidance also mentions that specific table games such as roulette can be excluded from a casino incentive, as long as that’s clearly stated. Read more on UK wagering cap rules and casino bonuses, or compare with our blackjack guide and live casino UK.
UK rules that apply
- Stake limits: the £5 / £2 online stake limits apply to slots, not roulette, so set your own stake limits.
- 10x wagering cap: bonus wagering can’t exceed 10 times (LCCP SR Code 5.1.1, from 19 January 2026).
- No credit cards: banned for gambling since 14 April 2020.
Staying in control
Online roulette can be played very quickly, and roulette stakes aren’t capped by the slot limits. Set a deposit limit before you play, decide in advance what you can afford to lose, and use reality checks and time-outs. Never chase losses. If you want a break from all UK-licensed gambling sites at once, GamStop is free and lets you self-exclude for 6 months, 1 year or 5 years. The National Gambling Helpline (0808 8020 133) is free, confidential and open 24 hours. More help: responsible gambling.
Frequently asked questions
What is the house edge on European roulette? 2.70% (1/37) on every standard bet.
What is the house edge on American roulette? 5.26% (2/38), and 7.89% on the five-number bet.
What does la partage do? It halves even-money losses when zero lands, cutting that bet’s edge to 1.35%.
Does any roulette system work? No. Each spin is independent and every bet keeps the same negative expectation.
Is red or black a better bet than a single number? Same edge on a single-zero wheel; it just wins more often for less.
Sources checked
Last checked 21 October 2026. Where we couldn’t confirm a fact on an official source, we’ve said so rather than guess.
- Gambling Commission – Socially responsible incentives: what operators need to know (12 December 2025)
- Gambling Commission – LCCP SR Code 5.1.1 Rewards and bonuses
- Gambling Commission – Online slots stake limit guidance
- Unibet – Free spins welcome offer
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