Roulette is a wheel game with fixed layouts and payouts. This guide explains the mathematics of standard single-zero and double-zero wheels using published rules. It does not provide a winning system: changing a stake pattern cannot change the probability built into a fair wheel.

Start with the Wheel and the Paytable

Roulette bets settle from the pocket where the ball lands. A standard single-zero wheel has 37 pockets: numbers 1–36 and 0. A double-zero wheel has 38: numbers 1–36, 0 and 00. These configurations and standard payouts are documented in the Nevada Gaming Control Board single-zero rules and double-zero rules.

Before placing a bet, open that game’s own rules and paytable. A branded, live, or feature version can use different rules or payouts, so a general guide cannot replace the information shown for the exact game.

What Does a Roulette Bet Cover?

Inside bets select specific numbers or small groups: a straight bet covers one number, a split covers two, a street covers three, a corner covers four, and a six line covers six. Outside bets cover wider groups, such as red or black, odd or even, low or high, dozens, and columns.

A wider bet can win more often because it covers more pockets, but its listed payout is lower. It does not change the result of a spin or create a reliable way to predict the next pocket.

How the Standard House-Edge Calculation Works

For a one-unit straight bet with a 35-to-1 payout, the net result is +35 units when the selected number lands and −1 unit otherwise. On a 37-pocket single-zero wheel, the expected value is (1/37 × 35) − (36/37 × 1) = −1/37, or about −2.70% per unit staked. On a 38-pocket double-zero wheel, it is (1/38 × 35) − (37/38 × 1) = −2/38, or about −5.26%.

These are long-run mathematical averages, not forecasts for a short session or an individual spin. They assume the standard wheel layouts and payouts described in the rules.

Why Outside Bets Still Include Zero Risk

A red/black, odd/even, or low/high bet normally covers 18 numbered pockets and pays 1-to-1. On a single-zero wheel, 18 winning pockets and 19 non-winning pockets give (18/37 × 1) − (19/37 × 1) = −1/37. On a double-zero wheel, the equivalent calculation is (18/38 × 1) − (20/38 × 1) = −2/38.

The zero or zeros are therefore material to the calculation. Check whether the exact game lists special treatment for zero on qualifying outside bets rather than assuming the edge is identical across versions.

Use Information for the Exact Game

The wheel type, eligible bets, payout table, and special rules should be visible before you commit a stake. UK Gambling Commission remote technical standards require information that lets customers make an informed decision about chances of winning, including rules and house edge, RTP, or probability, to be easily available before gambling.

Treat the displayed rules as the source for that table. If you choose to play, set a fixed entertainment budget in advance, do not chase losses, and stop when the budget or time limit is reached.