Inside vs. Outside Bets: Understanding the Roulette Table Layout
When you look at a roulette table for the first time, the sea of numbers and symbols can be overwhelming. However, the layout is logically divided into two primary sections: the inner grid of numbers and the outer perimeter of specialized boxes. These represent the two main categories of wagering: Inside Bets and Outside Bets.
The terms describe positions and number coverage on the layout. They do not distinguish safe bets from unsafe ones: every wager can lose. The examples below assume conventional payouts and a single-zero wheel unless stated otherwise.
Inside Bets: Numbers and Adjacent Groups
Inside bets are placed on the individual numbers (0 through 36) or the lines between them in the central area of the layout. These bets are characterized by lower mathematical probabilities of winning but significantly higher payout ratios. They are the “long shots” of the roulette world.
Popular Types of Inside Bets
- Straight Up: A bet on a single number. You place your chip directly in the center of the number’s box. Under conventional payouts, this covers one number and pays 35:1.
- Split: A bet on two adjacent numbers, placed by putting the chip on the line separating them. The payout is 17:1.
- Street: Covering three numbers in a horizontal row by placing the chip on the outer edge of that row. This pays 11:1.
- Corner (Square): A bet on four numbers that meet at a single point. The chip is placed on the intersection of the four boxes. The payout is 8:1.
- Six Line: Covering two adjacent rows (six numbers total). You place the chip on the outer T-junction where the two rows meet. This pays 5:1.
Probability of an Inside Bet
On a fair single-zero wheel, a specified number has probability 1/37, or approximately 2.70%, on each independent spin. The odds against are 36:1. Larger groups cover more pockets but pay less per winning stake.
Outside Bets: Playing the Probabilities
Outside bets appear around the number grid and cover categories such as colour, parity, ranges, dozens and columns. Greater number coverage increases winning frequency relative to a single-number bet, but does not protect a balance or guarantee a longer session.
Popular Types of Outside Bets
- Red or Black: Betting on the color of the winning pocket. This is an “even-money” bet, paying 1:1.
- Odd or Even: Betting on whether the number will be odd or even. This also pays 1:1.
- Low or High: Betting on whether the ball lands on 1-18 (Low) or 19-36 (High). Payout is 1:1.
- Dozens: There are three dozen-bet boxes: 1st 12, 2nd 12, and 3rd 12. These cover groups of twelve numbers and pay 2:1.
- Columns: At the end of the three long vertical columns are boxes for “Column Bets.” These cover all 12 numbers in that column and pay 2:1.
Outside Coverage Does Not Mean 50/50
Red, black, odd, even, low and high each cover 18 numbers. Dozens and columns each cover 12. Zero belongs to none of these categories for settlement purposes, even though zero is mathematically an even integer. The double zero is also excluded where present.
Payouts and Odds Comparison
To help our Canadian readers visualize the difference, we have compiled a quick reference table based on a standard European Roulette wheel (single zero).
| Bet Type | Example | Probability | Payout |
| Inside | Straight Up | 2.70% | 35:1 |
| Inside | Corner | 10.80% | 8:1 |
| Inside | Six Line | 16.20% | 5:1 |
| Outside | Dozens/Columns | 32.40% | 2:1 |
| Outside | Red/Black/Even/Odd | 48.60% | 1:1 |
The “Zero” Factor
A common misconception among new players is that Red/Black or Odd/Even are 50/50 bets. In reality, the green 0 pocket (and the 00 on American wheels) is what gives the house its edge. If the ball lands on the green zero, all even-money outside bets are lost (unless special rules like La Partage are in effect). This is why the probability for a Red/Black bet is 48.6% rather than 50%.
Combined Bets Must Be Counted Together
A winning component is not necessarily a profitable spin. Suppose $10 is staked on red and $1 on black number 2. If 2 wins, the straight-up bet returns $36 including its stake, while the red stake loses. Against $11 total stakes, the net gain is $25. If a red number wins, $20 is returned against the same $11 total, for $9 net gain. Other outcomes can lose both bets.
The example illustrates accounting, not a protective strategy. Adding stakes cannot make an outside bet pay for all session costs or establish a predictable “flow.”
House Edge and Exceptions
With conventional payouts, the listed single-zero bets share a house edge of approximately 2.70%, despite differing winning frequencies. La Partage and En Prison can change qualifying even-money settlements, while American roulette includes an additional zero and a distinct five-number basket exception.
See the probability guide for the calculations and the roulette glossary for layout terminology. WinnerOnline explains the rules and does not host tables.
Explore the full section: roulette betting systems and limitations.
