Roulette Odds and Bet Types Explained With the Real Maths

The wheel decides everything

Roulette maths starts with how many pockets the wheel has. A European wheel carries 37 pockets: the numbers 1 to 36 plus a single zero. An American wheel carries 38, because it adds a double zero. The payouts on both wheels are the same, which is exactly why the extra pocket matters so much.

Payouts versus probability

A straight-up bet on one number pays 35 to 1. On a European wheel the chance of hitting it is 1 in 37, so a fair payout would be 36 to 1. The missing unit is the casino's margin, and it works out at 2.70% of every stake on that wheel.

On an American wheel the same bet has a 1 in 38 chance while still paying 35 to 1, which pushes the edge to 5.26%. Two identical-looking tables can therefore charge roughly twice as much for the same game.

The standard bets and what they pay

• Straight up — one number, pays 35 to 1.
• Split — two adjacent numbers, pays 17 to 1.
• Street — three numbers in a row, pays 11 to 1.
• Corner — four numbers meeting at a point, pays 8 to 1.
• Six line — two adjacent rows, pays 5 to 1.
• Dozens and columns — twelve numbers, pay 2 to 1.
• Even-money bets — red or black, odd or even, high or low, pay 1 to 1.

On a European wheel every one of these carries the same 2.70% edge. Covering more numbers buys a higher hit frequency and a smaller payout; it does not buy a better price.

The even-money bets are not coin flips

Red and black look like a 50-50 proposition, but the zero belongs to neither. On a European wheel a red bet wins 18 times in 37, which is 48.65%, not 50%. That gap is the entire business model, repeated on every spin.

Where the edge can be genuinely lower

Some single-zero tables, usually labelled French roulette, apply la partage or en prison to even-money bets when zero lands. Under la partage half the stake is returned; under en prison the stake is held for the next spin. Either rule halves the edge on those specific bets to about 1.35%. It applies only to the even-money bets and only where the table rules say so, which is why the rules panel is worth opening before the first chip.

Systems and the memoryless wheel

Betting patterns built on previous results — following a streak of red, doubling after a loss, waiting for a number that is overdue — all rest on the same mistake. Each spin is independent, the wheel has no memory, and the edge is applied identically to every bet regardless of what came before. Progression changes the shape of your wins and losses, not their expected value.

Live and RNG versions

Online roulette exists as an RNG game and as a live-dealer table with a physical wheel. The mathematics above is identical in both. Game-show variants layer extra multipliers onto the standard wheel, and those change the paytable, so the specific rules and payouts of that version have to be read in its own information panel rather than assumed.

Play responsibly

Roulette is entertainment with a fixed, published cost per spin. Online play is for adults aged 18 or over, or the legal age in your jurisdiction. Set limits before playing, treat losses as spent and never chase them. If play stops being fun, free and confidential support is available from organisations such as BeGambleAware and GamCare.