Roulette is one of the most recognizable casino games in the world, thanks to its spinning wheel, its bouncing ball and its colorful layout. It is also a clean example of how probability and payouts fit together. This guide explains how the wheel works, what the main bets pay and where the built-in house edge comes from. It is for readers 18 and older and is informational only; gambling involves risk, and laws vary by state and country.

Two wheels, two different edges

The wheel has numbered pockets, each equally likely to catch the ball. The difference between the two common versions is the number of pockets:

European wheel: 37 pockets, numbers 1 to 36 plus a single zero.
American wheel: 38 pockets, numbers 1 to 36 plus a zero and a double zero.

That one extra pocket matters. The zeros are colored green and belong to no outside bet, so they give the casino its advantage.

What the main bets pay

Bets fall into two groups. Inside bets are placed on the numbers themselves, and outside bets cover bigger sections of the layout.

Straight-up (one number): pays 35 to 1.
Split (two numbers): pays 17 to 1.
Street (three numbers): pays 11 to 1.
Corner (four numbers): pays 8 to 1.
Red or black, odd or even, low or high: pays 1 to 1.
Dozens and columns (twelve numbers): pays 2 to 1.

The payouts are the same on both wheels. Only the number of pockets changes, which means the odds of winning are slightly worse on the American wheel.

Doing the math

Take a straight-up bet of $1. On a European wheel, you win $35 with probability 1/37 and lose $1 with probability 36/37. The average result is (35 × 1/37) − (1 × 36/37) = −1/37, or about −2.70%. On an American wheel, the same bet has an average result of (35 − 37)/38 = −2/38, or about −5.26%.

The same logic applies to a red-or-black bet. On a European wheel, 18 of 37 pockets win, so the chance is about 48.6%. On an American wheel, it is 18 of 38, or about 47.4%. In both cases the payout is 1 to 1, which is lower than the true odds would require.

The house edge in dollars

The percentages are long-run averages, not predictions for one session. As an illustration, if you wager a total of $100 over an evening on an American wheel, the expected loss is about $5.26. On a European wheel it is about $2.70. In a single night the actual result can be far above or below those figures because of variance, which is why short streaks can mislead; our explainer on variance and sample size covers this in more detail.

Special rules and the five-number bet

Two details are worth knowing:

The five-number bet. Some American layouts offer a bet on 0, 00, 1, 2 and 3 that pays 6 to 1. It wins 5 times in 38, so the average result is (5 × 6 − 33)/38 = −3/38, or about −7.89%, the worst bet on the table.
La partage or en prison. Some European-style tables return half of an even-money wager when the ball lands on zero, which roughly halves the edge on those bets to about 1.35%. Availability depends on the casino, so check the posted rules.

Myths worth dropping

The wheel has no memory. If red has come up five times in a row, the next spin is still independent, and the probabilities have not changed. No betting pattern, whether doubling after a loss or following a color streak, changes the house edge on each individual bet. Systems may change how quickly your bankroll swings, but they cannot turn a negative average into a positive one.

Play with limits

If you choose to play for entertainment, decide on a time and money limit in advance and treat the money as the cost of the activity. If gambling ever stops feeling like fun, our guide to the warning signs of problem gambling explains where to find help.

Frequently asked questions

Is European roulette really better for the player? By the numbers, yes. The house edge is about 2.70% versus 5.26% on the American wheel. Both are still negative for the player.

Which bet has the best odds? On a standard wheel, all main bets have the same house edge. Outside bets win more often but pay less, and inside bets win rarely but pay more.

Can a strategy beat roulette? No betting system can overcome the built-in edge on a fair wheel. Treat any claim of a guaranteed method as a red flag.

Steps

Identify the wheel: Count the pockets. A single zero means a 37-pocket European wheel; a zero and a double zero means a 38-pocket American wheel.
Learn the bet types: Inside bets cover specific numbers and pay more; outside bets cover large groups such as red or black and pay less.
Work out the true odds: Divide the number of winning pockets by the total pockets to see the real probability of each bet.
Compare with the payout: Notice that payouts are set below the true odds, and the gap is the house edge.