Before the layout: what kind of game this is
Roulette is a game of chance with a built-in house edge. No betting pattern, system or timing changes the odds in the player’s favor over time, and most players lose money over the long run. Nobody should gamble money they cannot afford to lose. If gambling is causing you or someone close to you difficulty, a local support service can help.
Understanding the layout does not give an advantage. It does make the rest of the game easier to follow, because every bet is defined by which pockets it covers, and the wheel and the table show those pockets in two different arrangements.
The wheel: pockets and their order
A roulette wheel is a shallow bowl with a spinning rim divided into numbered pockets. The dealer launches a small ball in one direction while the wheel turns the other way, and the ball eventually drops into a pocket. That pocket’s number is the result.
Two versions are common:
- A single-zero wheel has 37 pockets: the numbers 1 to 36 and one zero.
- A double-zero wheel has 38 pockets: the numbers 1 to 36, a zero and a double zero.
For layout purposes, the double zero is simply one more green pocket, though it raises the house edge noticeably.
The numbers are not placed in order around the wheel. On a single-zero wheel the clockwise sequence runs 0, 32, 15, 19, 4, 21, 2, 25, 17, 34, 6, 27, 13, 36, 11, 30, 8, 23, 10, 5, 24, 16, 33, 1, 20, 14, 31, 9, 22, 18, 29, 7, 28, 12, 35, 3, 26 and back to 0. Counting them gives 37 pockets, as it should. The sequence is arranged so that red and black alternate all the way around, apart from the green zero, and so that high and low numbers are spread out rather than bunched. The double-zero wheel uses a different order, with the two zeros placed on opposite sides of the wheel.
Colors
The zero pockets are green. Of the numbers 1 to 36, eighteen are red and eighteen are black. The red numbers are 1, 3, 5, 7, 9, 12, 14, 16, 18, 19, 21, 23, 25, 27, 30, 32, 34 and 36. The rest are black. The coloring follows a fixed pattern rather than a simple rule like “odd is red”, which is why it helps to see it on the felt rather than try to memorize it.
Color is only a label. A red pocket is not different from a black one in any way that affects where the ball lands, and the wheel does not “balance” colors from one spin to the next. Expecting it to is the gamblers fallacy.
The table: the betting grid
The felt shows the numbers in a different arrangement from the wheel. Numbers 1 to 36 are laid out in a grid of three columns and twelve rows, reading across each row: 1-2-3, then 4-5-6, and so on up to 34-35-36. The zero (or zeros) sits at the end of the grid, usually above the first row.
This grid is designed to make groups of numbers easy to bet on. The areas on the felt fall into two families.
The number grid
Chips placed on or between the numbers cover one or several pockets. A chip on one number covers that number alone. A chip on the line between two numbers covers both, a chip on the edge of a row covers the three numbers in that row, and a chip on the corner where four numbers meet covers all four. These are the inside bets, and each is priced by how many pockets it covers.
The surrounding boxes
Around the grid are larger boxes that cover bigger groups:
- Three dozens: 1 to 12, 13 to 24 and 25 to 36.
- Three columns: each box covers the twelve numbers in one vertical line of the grid, such as 3, 6, 9 and so on up to 36.
- Six even-money boxes: red, black, odd, even, 1 to 18 (low) and 19 to 36 (high).
The even-money boxes each cover 18 numbers. The zero pockets belong to none of them, which is the reason even-money bets are not truly even.
The racetrack and other extras
Many tables also show an oval strip of numbers, often called the racetrack, that follows the order of the wheel instead of the order of the grid. It exists because bets based on the wheel’s arrangement, such as a number and the pockets next to it, are awkward to place on a grid where those pockets are scattered. Grouped wagers of this kind are known as called bets.
Dealers, chips and table limits
Roulette tables usually give each player chips of a distinct color, so the dealer can tell whose bets are whose when the wheel stops. The chips carry no cash value away from the table, and the value of each color is set by the player when buying in. Tables post a minimum and maximum, and these often differ for inside and outside areas. These table limits matter more than they seem to, since they shape which betting patterns are even possible.
After the ball settles, the dealer places a marker on the winning number on the grid, clears the losing bets and pays the winners, then opens betting for the next spin. The marker is only for convenience.
Why the layout matters for the math
Every bet in roulette is a statement of the form “the ball will land in one of these pockets.” The layout simply gives you a convenient way to place that statement. Once you know how many pockets a bet covers and the payout ratios the table uses, you can work out its probability and expected value. As the later articles show, the payouts are set so that, on a given wheel, the cost is the same whichever area you choose. That is the idea behind the house edge, and the layout merely determines how many ways there are to pay it. Roulette probabilities follow directly from counting pockets: a bet covering n of 37 pockets wins with probability n/37.