How Do Roulette Probabilities Work?

A Hand With a Dice Cup and a Roulette Wheel Falling out of It

Real money roulette is one of the most popular games of chance, due to the fact that the odds are so much better in your favor than many other games at a casino. It’s a little overwhelming when there are so many different types of bets and the payouts differ depending on the probability of the bet you’ve placed.

In the following post, you will learn the basics of the different bets you can place, the payouts for each bet, and an overview of some strategies that are common to maximize the entertainment and chances of hitting it big at a roulette table.

American Roulette tables consist of 18 red numbers, 18 black numbers, a green 0, another green 00 space, and nine additional spaces that denote the less specific bets that are made (odds, evens, reds, blacks, etc).

Types of Bets

For this entry, we’ll cover the two most basic sets of roulette bets, known as outside bets and inside bets. There are also bets known as announced bets, which are more advanced and are uncommon in American Roulette. I won’t be covering those here.

An outside bet gives you the best odds, which also means the least payout. I would recommend that you get to know the table with these bets because you are more likely to win, even if you don’t win as much as you would with inside bets.

Outside Bets

There are five different common types of outside bets in real money roulette as follows: red or black, odd or even, 1 to 18 or 19 to 36, dozens, and columns. There’s also another, less common bet considered an outside bet called a snake bet.

With red or black, you place your bet on the corresponding space. The odds are not quite 50/50 due to the 0 and 00 spaces. Because you have 38 total numbers (1 through 36, 0, and 00) and 18 total numbers which are red or black, the odds are 18 out of 38,w hich equals 47.37%. Your payout for such a bet will be 1 to 1, which means if you bet $1 on red and a red number is the winner, you get your $1 back plus an additional $1.

Odd or even have the exact same odds and payouts, as do 1 to 18 and 19 to 36.

A Roulette Rake Moving Chips

When it comes to the dozens, you place your bet on the corresponding choice of first 12, second 12, or third 12. Now, your payout gets a little more lucrative if you win because your chances are substantially less (one-third less, to be precise). Your probability goes from 47.37% to 31.58% (12 out of 38). Your payout is now 2 to 1, meaning you’ll get a total of triple your bet were you to win this type of bet.

When placing a bet for a column, you place your chip in one of the spaces on the table that specify 2 to 1, depending on which column contains the number you believe will win. Columns have a similar relationship to dozens like red or black has to even or odds, meaning that your probability is 31.58% and your payout is again 2 to 1.

A snake bet is typically a bet on red numbers 1, 5, 9, 12, 14, 16, 19, 23, 27, 30, 32, and 34, creating the shape of a snake. Like the dozens and columns, this bet has a probability of 31.58%. In this bet, all of the numbers are covered by one chip, and the payout is 2 to 1.

Inside Bets

There are seven different common inside bets. These bets have a lower chance of payout, but that being the case, your payout will be higher. The types of inside bets we’ll cover here are straight, split, street, six line, corner, trio, and basket.

Straight and Split

A straight bet is one which only covers one number. In order to place this bet, you’ll place your chip inside the space with the corresponding number. The odds of this bet are 1 out of 38, or 2.63%. Your payout for this type of inside bet is 35 to 1, which means if you select the winning number, you will get your bet times 36.

A split bet is one in which you are betting on two different numbers which are adjacent on the table. This bet is made by placing your chip on the line that separates the adjacent numbers you’ve chosen. Your odds are better on a split bet by double, so your payout follows suit, being about half that of the single: 2 out of 38 equals 5.26% and your payout is 17 to 1.

Street and Six

A street bet is a bet on three consecutive numbers located on the same line. In order to place this bet, you would place your chip on the outer corner of the row you have chosen. Now, your odds are triple that of a straight bet, so again, your payout also follows suit, being about a third of the payout for a straight bet: 3 out of 38 equals 7.89% with a payout of 11 to 1.

The six line bet has a similar relationship to the street bet in the way that the straight bet has to a split bet. You place the bet on two adjacent lines. In order to place a six line bet, you’ll place your chip on the common outer corner of the two lines that you have chosen to bet on. Again, your odds are doubled, therefore, your payout is halved: 6 out of 38 equals 15.79% with a payout of 5 to 1.

Corner, Trio, and Basket

A corner bet is basically like splitting a split bet. This is a four-number bet which is placed by putting your chip on the common corner of the four numbers. This is also known as a square bet. Because the odds are doubled over a split bet, the payout also follows suit. Therefore, your probability is 4 out of 38, or equal to 10.53% with a payout of 8 to 1.

A trio bet is a three-number bet that includes the zeros. In order to place this bet, you’ll place your chip on the line shared by the zero box and the two other numbers. In this case, the probability lies at 3 out of 38, or 7.89% with a payout of 11 to 1.

Finally, a basket bet is a five-number bet which allows a player to bet on the zero, double zero, and 1, 2, and three. To place this bet, place the chip on the corner of the one and zero. Here the probability is 5 out of 38, or 13.16% with a payout of 6 to 1.


There are many strategies for playing roulette, and as you play, you might as well develop your own unique system. It’s likely, though, that anything you find to work has been used many times by other players.

The first strategy I’ll cover here is called the Martingale Strategy. Basically, this strategy is used in all types of gambling and is summed up by the statement ,“I have to win sooner or later, right?” The simple answer to this is a case of, “Yes, if…” and the more complicated conclusion is ,“No, but…”

The strategy is very simple. A player doubles his bet if he loses in hopes of making up the loss. For example, if you place an initial bet of $10 and lose, betting $20 on the next bet will recoup your loss and give you the $10 win.

Some players will continue down the line. So, it could go like this: $10 loss, $20 loss, $40 loss, $80 loss, then a $160 win. After adding up the losses, you’ve lost $150, and won back the $160 final bet, netting you a total of $10.

The problem is that you can rack up a large amount of losses, and many casinos and tables have a maximum bet. So, if you get up to $640 without a single win and the maximum bet is $1,000, even a win on that bet will still have you down $270.

The next strategy you might like to try is the Paroli Strategy. It’s what’s known as a positive betting system. With this, your aim is to increase your bet after a win and keep increasing the bet as the wins increase.

Most players do this in increasing rounds of three. First, bet $10, then another $10, followed by a $20, followed by a $40. If all of these bets win, you’ll be at $80 up. Usually after a streak like this, you’d go back to your original $10 bet.

Always keep in mind that the house has an edge no matter which game you’re playing. The way these folks stay in business is by adhering to the science of numbers, which have no sympathy, and on a long enough timeline, do not vary.


Roulette is a great way to get started with table games and has great odds compared to games like slots. The payouts can be enormous, and it’s a simple way to get started with different strategies. There are also great places to play online.

Do you see any roulette strategies I missed? Let me know in the comments!