Roulette Odds Calculator & Probability Guide
Calculate your exact win probability, expected return, and risk level. Before you play at UK online roulette sites, use this tool to compare the true mathematical odds of every bet on the table against the casino payout.
Last Updated: February 2026 • Verified by: Roulette UK Team
Interactive Bet Calculator
Select your wheel type (European is standard for UK) and bet to see the House Edge.
🎡 Roulette Odds & Payout Calculator
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How to Use the Roulette Odds Calculator
An odds calculator doesn’t predict the future; it reveals the mathematical viability of your betting structure. Use the tool above to optimize your bankroll management before sitting down at a live table:
- Step 1: Select the Wheel Variant. Always toggle the calculator to “European” if you are playing in the UK. Switching it to “American” will immediately demonstrate how the extra double-zero (00) degrades your win probability across all bet types.
- Step 2: Input Your Base Unit. Enter your standard chip size (e.g., £5). The calculator will output your exact potential profit versus the statistical risk of losing that stake.
- Step 3: Analyze the Expected Value (EV). Use the tool to compare combining multiple inside bets (like 4 corners) versus a single outside bet (like a Dozen). You will quickly see that while coverage increases, the fundamental house edge remains static.
The Mathematics of Roulette: True Odds vs. Casino Payouts
To become a smarter player, you must understand the difference between “Odds of Winning” (Probability) and “Casino Payouts.” The gap between these two numbers is the House Edge—the fee you pay to play.
1. True Odds (The Real Math)
On a standard European Roulette wheel, there are 37 pockets (Numbers 1–36, plus a single Green 0).
- If you bet on a single number (e.g., Number 7), you have 1 chance in 37 of winning.
- Mathematically, the “True Odds” against you are 36 to 1.
2. Casino Payouts (What You Get Paid)
If your number hits, the casino does not pay you 36 to 1. Instead, they pay you 35 to 1.
This discrepancy—paying 35 units when the true risk is 36 units—is how the casino guarantees a profit. On every spin, the presence of the Zero ensures that the “Even Money” bets (Red/Black) are never truly 50/50. They are actually 48.65% to win vs 51.35% to lose.
Expected Value mathematically represents what you stand to win or lose per bet in the long run. The formula is: $EV = (Probability of Winning \times Payout) – (Probability of Losing \times Stake)$. If you bet £10 on Red on a European wheel: $(18/37 \times £10) – (19/37 \times £10) = -£0.27$. This means for every £10 wagered, you mathematically forfeit 27 pence to the house.
American tables add a Double Zero (00), bringing the total pockets to 38. The payout remains 35 to 1, but your true odds worsen to 37 to 1. This nearly doubles the casino’s advantage from 2.70% to 5.26%. Always play European.
The Probability of Betting Systems
Many players use roulette betting strategies like the Martingale or D’Alembert to try and beat the odds. While these systems manage your bankroll, they cannot change the game’s probability. Here is the mathematical reality of common system scenarios.
1. The “Martingale” Probability of Ruin
The Martingale involves doubling your bet after a loss to recover funds. It relies on the idea that “Red has to hit eventually.” However, long losing streaks are statistically more common than players realize.
- Odds of 5 Reds in a Row: 1 in 32 (Approx 3%)
- Odds of 8 Reds in a Row: 1 in 263 (Approx 0.4%)
- Odds of 10 Reds in a Row: 1 in 1,376 (Approx 0.07%)
While 0.07% sounds rare, in a session of 1,000 spins (typical for an hour of speed roulette), there is a significant chance you will encounter a streak of 10. If you started with a £5 bet, your 10th bet would need to be £2,560. Most tables have a £1,000 or £2,000 limit, meaning the Martingale fails mathematically due to table caps.
2. The “Gambler’s Fallacy”
This is the false belief that past results influence future spins. “Black has hit 5 times, so Red is due!”
Complete Payout & Probability Charts
Use this reference table to plan your betting strategy. Notice how “Coverage” correlates inversely with “Payout.” High coverage means safer bets but lower returns.
European Roulette Odds (Single Zero | 2.70% Edge)
| Bet Name | Numbers Covered | Payout Ratio | Win Probability |
|---|---|---|---|
| Straight Up | 1 | 35 to 1 | 2.70% |
| Split | 2 | 17 to 1 | 5.40% |
| Street | 3 | 11 to 1 | 8.10% |
| Corner (Square) | 4 | 8 to 1 | 10.80% |
| Six Line | 6 | 5 to 1 | 16.20% |
| Dozen / Column | 12 | 2 to 1 | 32.40% |
| Even Money | 18 | 1 to 1 | 48.60% |
American Roulette Odds (Double Zero | 5.26% Edge)
Notice how the Win Probability drops across every single bet type, despite the payout remaining identical to the European wheel. This is why American roulette is highly detrimental to your bankroll.
| Bet Name | Numbers Covered | Payout Ratio | Win Probability |
|---|---|---|---|
| Straight Up | 1 | 35 to 1 | 2.63% |
| Basket Bet (Top Line) | 5 (0, 00, 1, 2, 3) | 6 to 1 | 13.16% (Worst Edge: 7.89%) |
| Even Money | 18 | 1 to 1 | 47.37% |
Call Bets: Covering Sections of the Wheel
Advanced players often use “Call Bets” (announced bets) found on the Racetrack section of the table. These bets cover specific physical sections of the wheel rather than the numerical order on the felt.
Voisins du Zéro (Neighbors of Zero)
Coverage: 17 Numbers (45.9%)
This covers the large arc of numbers surrounding the Zero. It requires 9 chips to place. It is a high-coverage bet often used by players who believe the dealer is aiming for the Zero sector.
Tiers du Cylindre (Thirds)
Coverage: 12 Numbers (32.4%)
This covers the wedge of the wheel directly opposite the Zero. It requires 6 chips (all splits). It offers a steady 32.4% win rate, identical to betting on a Dozen but spread differently.
Orphelins (Orphans)
Coverage: 8 Numbers (21.6%)
This covers the two small slices of the wheel not covered by Voisins or Tiers. It requires 5 chips. Because 4 of the chips are splits and 1 is a straight up, the payout varies depending on which number hits.
Jeu Zéro (Zero Game)
Coverage: 7 Numbers (18.9%)
A localized, cheaper version of Voisins. It covers the zero and the 6 numbers immediately closest to it on the wheel (12, 35, 3, 26, 0, 32, 15). It costs just 4 chips to play.
How to Reduce the House Edge (Legally)
You cannot cheat the physics of the wheel, but you can choose rules that mathematically lower the casino’s advantage. This is the single most effective “system” for long-term play.
1. Find “La Partage” Tables
This rule is unique to French Roulette. If you place an Even Money bet (Red/Black) and the ball lands on Zero, you do not lose everything. Instead, half your stake is returned to you.
- Standard Edge: 2.70%
- La Partage Edge: 1.35%
This makes French Roulette one of the best value games in the entire casino, rivaling Blackjack and Baccarat.
2. Avoid Side Bets
Online roulette games often feature side bets like “Perfect Pairs” or “Hot Properties.” While tempting with high payouts (e.g., 500:1), these bets typically carry a massive House Edge of 10% to 15%. Stick to the main table layout for the best mathematical returns.
🛡️ Play Safe: Responsible Gambling
Roulette is a negative expectation game. This means that over an infinite number of spins, the math dictates that the casino will win. Short-term variance allows players to win, but you should never treat roulette as a source of income.
Managing Your Bankroll
To play safely, we recommend the “5% Rule”. Never bet more than 5% of your total session bankroll on a single spin. If you have £100 to play with, your maximum bet should be £5. This ensures you can survive natural losing streaks without busting out immediately.
UK Support Resources
If you feel your gambling is becoming a problem, use these free UK resources:
- GAMSTOP: A free self-exclusion tool that blocks you from all UK-licensed gambling sites for 6 months, 1 year, or 5 years.
- BeGambleAware: Confidential help and support for anyone worried about their gambling.
- GamCare: The leading provider of information, advice, and support for the prevention and treatment of problem gambling.
Frequently Asked Questions
What is the best bet in roulette?
Mathematically, the Even-Money bets (Red/Black, Odd/Even) on a French Roulette table with “La Partage” are the best. They offer a 48.65% win probability and a low house edge of 1.35%.
Why does the American wheel have worse odds?
The American wheel adds a Double Zero (00) pocket. This extra number dilutes your winning chances without increasing the payouts. The house edge jumps from 2.7% (European) to 5.26% (American). Always avoid American wheels online.
What are the odds of hitting Green Zero?
On a European wheel, the odds of hitting Zero are 1 in 37 (2.70%). If you bet on Zero straight up, it pays 35:1. If you bet on Red/Black, Zero is a loss (unless La Partage applies).
What is the worst possible bet in roulette?
The “Basket Bet” (or Top Line) on an American Roulette wheel. It covers the 0, 00, 1, 2, and 3. It pays 6:1 but carries an astronomical house edge of 7.89%, making it statistically the fastest way to lose your money.
Can a calculator predict the next number?
No. Roulette calculators show you the payouts and mathematical probability of a bet winning. They cannot predict where the ball will land, as each spin is an independent random event.
Is online roulette rigged?
Licensed UK casinos use RNG (Random Number Generator) software that is audited by independent agencies like eCOGRA. This ensures the result of every spin is statistically random and fair, mirroring a physical wheel. Always check the odds on live dealer tables as well.