The Calculation Starts at the Wheel, Not the Table
Most people walk up to a roulette table and look at the felt first. The real calculation happens one step earlier, on the wheel itself. Roulette odds are built from a simple relationship: the number of pockets a bet covers versus the number of pockets the bet does not cover. The table layout is just a map of that relationship.
A European wheel carries 37 pockets, numbered 0 through 36 with a single zero. An American wheel carries 38, adding a double zero. That extra pocket is not a cosmetic difference. It changes the arithmetic on every bet you can place, because the payout printed on the felt stays the same while the number of losing pockets goes up by one.
To calculate any roulette bet, you need two numbers: how many pockets your wager covers, and how many pockets exist on the wheel you are standing at. Everything else follows from those two.
Reading a Payout as a Ratio
Roulette payouts are written as ratios, and the ratio is always stated from the player's side. A straight-up bet on a single number pays 35 to 1. A split covering two numbers pays 17 to 1. A street covering three pays 11 to 1. These printed payouts are fixed by the game's design and do not change between wheels.
The ratio means this: a winning straight-up bet returns your original stake plus 35 times that stake. If you bet one unit and win, you receive 36 units back in total. The 35 is the profit; the extra 1 is your own wager being returned. New players sometimes read 35 to 1 as receiving 35 units total, which undercounts the return by the amount of the original bet.
The calculation for what a bet should pay if the wheel were perfectly fair is also a ratio. On a European wheel, a single number covers 1 pocket out of 37. A fair payout would be 36 to 1, because there are 36 ways to lose and 1 way to win. The table pays 35 to 1 instead. That one-unit gap, applied across every spin, is the house edge expressed as a structural fact rather than a percentage you need to memorise.
Bet Types and What They Cover
Roulette bets fall into two families. Inside bets sit on the numbered grid and cover specific numbers or small groups of them. Outside bets sit around the grid and cover broad categories: red or black, odd or even, high or low, columns, and dozens.
Each bet type covers a different number of pockets, and the payout shrinks as the coverage grows. A straight-up bet covers one pocket and pays the most. A red or black bet covers eighteen pockets and pays even money. The table below lays out the main bet types, how many pockets each covers on a European wheel, and the printed payout.
| Bet type | Pockets covered (European wheel) | Payout | What it means |
|---|---|---|---|
| Straight-up | 1 | 35 to 1 | A single number |
| Split | 2 | 17 to 1 | Two adjacent numbers |
| Street | 3 | 11 to 1 | A row of three numbers |
| Corner | 4 | 8 to 1 | Four numbers meeting at a corner |
| Six line | 6 | 5 to 1 | Two adjacent rows |
| Dozen or column | 12 | 2 to 1 | Twelve numbers as a block or column |
| Red/black, odd/even, high/low | 18 | 1 to 1 | Eighteen numbers by category |
On an American wheel, every one of these bets still covers the same number of pockets, but the wheel now has one more pocket that none of them cover. The payout does not rise to compensate. That is why the same bet carries a different expected loss depending on which wheel you are playing.
Calculating What a Bet Returns
The calculation a player can do at the table has two parts. The first is simple and exact: multiply your stake by the payout ratio, then add your stake back. A three-unit street bet that wins pays 11 times 3, or 33 units of profit, plus the 3 units you wagered, for a 36-unit total return.
The second part is the expected value over many spins, and it is the part that tells you what the bet costs to make. Take the number of winning pockets, multiply by the payout, and compare that to the number of losing pockets. On a European wheel, a straight-up bet has 1 winning pocket paying 35 units and 36 losing pockets taking 1 unit each. Across 37 spins with each number appearing once, you would wager 37 units and receive 36 back. The missing unit is the structural cost of the bet.
That cost is not a fee the casino adds at the end. It is built into the payout ratio itself. The payout is always slightly short of what the wheel's true odds would require, and that shortfall is the operator's mathematical advantage on the wager.
Where the House Edge Comes From
House edge and Return to Player are complements: they sum to 100% for the same bet under the same rule set. On a European wheel, the single zero creates the gap. On an American wheel, the double zero widens it. The printed payouts are identical on both wheels, so the wheel with more pockets produces a larger gap for the house on every bet that does not cover the extra pocket.
This is why two roulette tables in the same building can carry different edges. The felt looks the same, the payouts read the same, but the wheel behind the dealer determines the arithmetic. Before you sit down, look at the wheel itself. A single zero means one calculation. A double zero means another, less favourable one.
No betting pattern changes this. Covering more numbers reduces variance, because you win more often, but each bet you place still carries its own edge. A player who covers red and black on the same spin has not created a safe position; they have placed two even-money bets, each with its own expected loss, and the zero pocket still sits outside both of them.
The Sequence of a Round
A round of roulette moves through a fixed sequence, and knowing it helps you avoid procedural mistakes that cost real money. The dealer opens betting, players place chips on the layout, the dealer closes betting, the ball is spun, the winning number is marked, losing bets are cleared, and winning bets are paid.
Buy-in happens before any of that. You place cash on the table, never into the dealer's hand, and the dealer exchanges it for wheel chips. Some venues give roulette chips a distinct colour per player so that bets at the same spot can be told apart. Those chips have no value at other tables, so you must exchange them back for regular casino chips before you leave the roulette table.
Decision points are limited. You choose which bets to place and how much to stake on each. You may place multiple bets on the same spin. What you cannot do is place a bet after the dealer calls no more bets, touch chips once the ball is in motion, or move a losing bet after the number is called. Each of those is a fast way to have a bet voided or to be corrected by the pit staff.
Mistakes That Cost More Than the Edge
The first mistake is arithmetic: reading a payout as the total return rather than the profit. A player who thinks 35 to 1 means 35 units back will undercount their return on every winning straight-up bet. The stake always comes back with the winnings.
The second mistake is wheel confusion. Sitting at an American wheel while calculating European odds means every bet costs more than the player believes. The wheel, not the felt, is the source of truth. Check for the double zero before you calculate anything.
The third mistake is betting on categories without knowing what they exclude. A red or black bet covers eighteen numbers, but the zero pockets are neither red nor black for payout purposes. An odd or even bet excludes the zeros as well. A player who believes an even-money bet covers half the wheel is counting pockets that do not pay.
What a Strategy Chart Can and Cannot Do
Roulette does not have a decision chart in the way blackjack does. There is no choice about whether to hit or stand, no dealer upcard to read. The only decisions are which bets to place and how much to stake. What roulette does have is a payout table, and that table is fixed.
Any published roulette strategy that claims to overcome the wheel's arithmetic is describing a betting progression, not a change to the odds. Progressions alter the size and timing of wagers. They do not alter the number of pockets on the wheel or the payout printed on the felt. A progression can change how wins and losses are distributed across a session, but the expected loss per unit wagered remains the same on every spin.
The useful calculation is the one you do before the first chip goes down: know the wheel, know the payout ratio, and know that the gap between the two is the cost of playing. Everything after that is variance.
FAQ
How do I calculate my roulette winnings on a split bet?
Multiply your stake by the printed payout for a split, which is 17 to 1, then add the original stake back. A two-unit split that wins returns 34 units of profit plus the 2 units wagered, for 36 units total. The same method applies to every roulette bet: payout times stake, plus stake.
Does the zero count as red or black when calculating even-money bets?
No. The zero pockets sit outside the red and black categories, and outside odd and even as well. An even-money bet on red covers the eighteen red numbers only. When the ball lands in a zero pocket, red, black, odd, and even bets all lose unless the table rules state otherwise.
Why does the same bet pay the same on both wheels if the odds are different?
Because the payout ratios are fixed by the game's design and printed on the layout. The wheel behind the dealer determines how many pockets exist, but the felt does not change its payouts to match. The American wheel adds a pocket without raising any payout, which is why the same bet carries a larger expected loss there.
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This article is general information about how these mechanics work. It is not legal advice and not a recommendation to gamble or to use any particular operator. Availability and legality differ by jurisdiction — check the rules that apply where you are.