Roulette Bets Explained: Inside vs Outside Bets and Odds

This article explains roulette bets so that you understand not just what each wager pays, but why the payouts are what they are and how the casino builds its margin into every single option. Whether you are standing at a table for the first time or you have been playing for years and want to see the mathematics laid out clearly, knowing the probabilities behind each bet helps you make deliberate choices about variance and bankroll rather than guessing.

Inside bets vs outside bets: the basic split

The layout of a roulette table divides naturally into two zones, and the names of the bet categories come directly from where you place your chips. The inner grid of numbered pockets, running from 1 to 36 arranged in three columns of twelve, is the “inside” area. The outer perimeter, where you find the boxes for red and black, odd and even, high and low, and the dozens and columns, is the “outside” area. That spatial distinction is all the naming convention comes from, but it maps onto a genuine structural difference in risk profile.

Inside bets cover fewer numbers per chip. A single chip on a straight-up number covers exactly one of the thirty-seven pockets on a European wheel (or thirty-eight on an American wheel). Because you are betting on a narrow outcome, the casino pays you more generously when you win. Outside bets cover more numbers per chip. A chip on “red” covers eighteen pockets. Because the probability of winning is much higher, the casino pays you less when you win.

This inverse relationship between probability and payout is the fundamental arithmetic that governs all of roulette. No bet pays more than its fair odds would dictate, and the gap between the true odds and the casino’s payout is where the house edge lives. The edge itself does not change between inside and outside bets on a standard European wheel, but the volatility does. Inside bets swing hard: long dry stretches punctuated by large wins. Outside bets deliver a smoother ride with smaller wins and fewer dramatic peaks.

Some players mistakenly believe that outside bets are “safer” in the sense that they lose less money over time. This is not true. A player betting exclusively on red on a European wheel faces exactly the same 2.70% house edge as a player betting exclusively on individual numbers. The difference is entirely in variance: how much your bankroll fluctuates before the long-run mathematical expectation reasserts itself. In the short run, outside-bet players feel steadier, but the rate at which they lose money per unit wagered is identical to inside-bet players.

There is no moral hierarchy between the two categories. Some people prefer the high-variance thrill of inside bets because the potential for a single large win exists. Others prefer outside bets because the experience feels more like an even contest, with roughly half the spins producing a win. Neither approach beats the math. Both lose at exactly the same percentage rate of total amount wagered. The choice should be based on how much variance you are comfortable with and how long you want to play with a given bankroll.

Inside bets and their true payout odds

There are six standard inside bets in roulette. Each one covers a different number of pockets, and each one has a different payout ratio that corresponds to how narrow or broad its coverage is. The table below lists every inside bet along with its payout, the number of pockets it covers, and the exact probability of winning on a European wheel (single zero, thirty-seven pockets total).

Notice the pattern in the “True Odds Against” column. If a bet covers one number out of thirty-seven, the fair payout would be 36 to 1 (because the casino would need to return your stake plus 36 units for the game to be break-even over the long run). Instead, the casino pays 35 to 1. That one-unit gap is the house edge, and it exists on every single bet type in the same proportion relative to the payout.

Let me explain each bet type briefly so you know what to ask the dealer or where to place chips.

Straight up is the simplest: one chip placed entirely within the box of a single number. If that number comes up, you win thirty-five times your stake. If anything else comes up, you lose the chip. This is the highest-variance bet in roulette and the one most people picture when they think of a roulette win.

A split is made by placing a chip on the line between two adjacent numbers on the layout. Both numbers now count as winners. The chip physically straddles the border, which is what signals to the dealer what bet you are making.

A street covers three numbers that sit horizontally next to each other on the layout (for example, 1-2-3 or 16-17-18). You place your chip on the outer edge of the row, in the small box that borders the three numbers on the left side of the grid. This is sometimes confused with a “line bet,” which refers to the six-line.

A corner (also called a “square”) covers four numbers that meet at a single point on the grid. Place your chip on the intersection where four boxes meet. For instance, numbers 10, 11, 13, and 14 share a corner.

The six line (or “double street”) covers two adjacent rows of three numbers each, for a total of six numbers. You place the chip on the corner where the outer edge of one row meets the inner line between two rows. This gives you the broadest coverage of any inside bet.

On an American wheel with thirty-eight pockets, every probability in the table shifts slightly. A straight-up bet becomes 1 in 38 rather than 1 in 37. The payouts stay the same, but the house edge rises from 2.70% to 5.26% because the extra zero pocket adds losing outcomes without adding to your potential return.

Outside bets and their true payout odds

Outside bets are named for their position on the table layout, and they all cover substantially more pockets than inside bets. There are five standard outside bets, and on a European wheel they all carry the exact same 2.70% house edge as every inside bet. The difference is purely in the risk-reward shape: you win more often, but each win is smaller relative to the amount you stand to lose on any given spin.

Here is a reference for each outside bet type. The probabilities assume a European wheel with thirty-seven pockets. For American wheels, replace 37 with 38 and the percentages will adjust accordingly (red drops from 48.65% to 47.37%, and so on).

Red or Black covers eighteen pockets. The probability of winning on a European wheel is 18/37, which equals approximately 48.65%. The payout is 1 to 1, meaning you double your money. The true odds against winning are 19:18, but the casino pays even money. This is the classic coin-flip bet, except it is not quite a coin flip because of the single zero.

Odd or Even works identically to red/black in terms of coverage and mathematics. Eighteen odd numbers out of thirty-seven pockets give you 18/37 probability, 1-to-1 payout, and 48.65% chance of winning. The zero is neither odd nor even by convention, which is why it counts as a loss for both the odd and even bets.

High or Low divides the numbers from 1 to 18 (low) and 19 to 36 (high). Each covers eighteen pockets. Again, zero sits outside both groups and causes a loss. The probability and payout are identical to red/black and odd/even.

Dozens covers twelve numbers. First dozen is 1 through 12, second dozen is 13 through 24, third dozen is 25 through 36. You can place one chip to cover any single dozen. Probability is 12/37, approximately 32.43%, and payout is 2 to 1. True odds against winning are 25:12, so the casino pays less than fair odds, producing the same 2.70% edge.

Columns covers twelve numbers as well, but in a different arrangement. The layout has three vertical columns of twelve numbers each. Column one is 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34. Column two is 2, 5, 8, and so on. You place your chip in the “2 to 1” box at the bottom of the column. Mathematically identical to dozens: 12/37 probability, 2-to-1 payout, 32.43% win rate.

One practical note: on a standard table, you can place chips on multiple outside bets simultaneously. For example, you could cover both red and the second dozen at the same time. These are independent bets, not a single combined wager. If the ball lands on 14 (which is red and in the second dozen), you win both. If it lands on 5 (which is red but in the first dozen), you win the red bet and lose the dozen bet. You can also deliberately combine outside bets to reduce your total risk per spin, though the house edge per dollar wagered remains unchanged.

A common question is whether you can cover the entire table by betting all three dozens, or red and black, and whether this eliminates the house edge. It does not. If you bet ten units on each dozen (thirty units total), you win twenty units on a dozen hit and lose thirty on zero. Over thirty-seven spins, you lose exactly one full cycle of your bet size. You have converted the house edge into a certainty rather than a probability, and your maximum loss per spin equals thirty units. This is a terrible trade for the math.

Why every bet on the wheel has the same house edge

This is the question that many players find counterintuitive, and understanding the answer is genuinely valuable for anyone playing roulette or any similar game. The house edge is not a number that varies from bet to bet on a European roulette wheel. It is 2.70% on every single standard wager. Here is why, shown through the arithmetic.

Take the simplest case: a straight-up bet of one unit. On a European wheel, you have 1/37 chance of winning and 36/37 chance of losing. If you win, you receive 35 units profit plus your one unit stake back, for a total return of 36 units. If you lose, you lose your one unit. The expected value of this bet is:

(1/37 × 36) + (36/37 × 0) − 1 = 36/37 − 1 = −1/37 ≈ −0.0270

That means for every unit you wager on a straight-up number, you can expect to lose 0.027 units on average. That is a 2.70% house edge.

Now take a red bet of one unit. You win 18/37 of the time, gaining 1 unit profit (and your stake back). You lose 19/37 of the time (the eighteen black numbers plus the single zero). Expected value:

(18/37 × 2) + (19/37 × 0) − 1 = 36/37 − 1 = −1/37 ≈ −0.0270

Identical result. Now try a dozen bet. You win 12/37 of the time, gaining 2 units profit plus your stake. You lose 25/37 of the time. Expected value:

(12/37 × 3) + (25/37 × 0) − 1 = 36/37 − 1 = −1/37 ≈ −0.0270

The pattern is unmistakable. For every possible payout structure, the numerator of the expected return is always 36 (the total number of non-zero outcomes times the stake), and the denominator is always 37 (the total number of pockets). The zero pocket contributes a loss to every bet type but contributes nothing to any win, which creates the fixed fractional disadvantage of one thirty-seventh.

On an American wheel, the same logic applies with thirty-eight pockets. Expected value becomes (n × payout_factor) / 38 − 1 for any bet covering n winning pockets. This always resolves to −2/38 = −1/19 ≈ −5.26%, because the two zero pockets both cause losses without adding to any winning coverage.

There is exactly one exception to the uniform house edge rule, and it exists only on American wheels. The five-number bet (covering 0, 00, 1, 2, and 3) pays 6 to 1. Expected value: (5/38 × 7) − 1 = 35/38 − 1 = −3/38 ≈ −7.89%. This is dramatically worse than every other bet on the table. Some casinos do not offer this bet at all because of how obviously disadvantageous it is, but where it exists, avoid it entirely. The five-number bet is the only wager on a roulette table where the house edge is not the same as every other bet, and it is strictly worse.

On European and French wheels, there is no equivalent exception. Every single bet type carries exactly 2.70% edge, and if the wheel uses the “en prison” or “la partage” rules for even-money bets when the ball lands on zero, the effective house edge on those specific bets drops to approximately 1.35%. This is the best version of roulette available anywhere, and if you have the choice between a French-style European wheel and any other configuration, that choice matters more than any strategy you might employ.

Combining bets: does it change your odds?

Players often wonder whether placing multiple bets simultaneously creates a mathematical advantage. The short answer is no: the house edge applies independently to each unit wagered, regardless of how many bets you place or how they overlap. The longer answer is more interesting because combinations do change your experience at the table even though they do not change the mathematics.

When you place multiple bets on a single spin, you are simply making several independent wagers that happen to resolve on the same outcome. The casino calculates and settles each one separately. If you put one unit on 17 (straight up) and one unit on column two (an outside bet), those are two completely separate contracts with the house. Your total risk per spin is two units, and your expected loss per spin is 2 × 2.70% = 0.054 units on a European wheel. The combination did not reduce or increase your edge; it only changed the distribution of possible outcomes on any given spin.

What combinations do change is your variance and your hit frequency. A player who spreads ten units across a single number and the dozen it belongs to has a very different session profile than a player who places those ten units on ten different outside bets. The first player loses most spins and occasionally wins big. The second player wins on roughly half of all spins with modest profit and loses the other half. Both players surrender the same percentage of total amount wagered over enough spins, but the second player’s bankroll curve looks smoother and the first player’s looks jagged.

One popular pattern worth addressing directly: some players place chips on all three dozens plus the zero, believing this creates a net-positive outcome. It does not. Betting one unit on each dozen costs three units. If any dozen hits, you win two units profit from that dozen but lose two units from the other two dozens, netting zero (plus you lose your zero bet). The entire purpose of adding zero is to cover the one outcome where all three dozen bets lose, but the cost of that insurance always exceeds its expected value. You are simply converting a probabilistic loss into a smaller, more consistent certain loss.

Another common combination: covering red, black, odd, and even simultaneously. You are wagering four units to guarantee a return of four units on any non-zero outcome (you win two bets and lose two, netting zero profit after costs) and losing all four on zero. This is strictly worse than making no bets at all, because you have created a scenario where you either break even or lose money. There is no outcome where you profit.

The reason these combinations fail is the same principle that governs single bets: the zero pocket is the casino’s margin, and no arrangement of coverage among the numbered pockets eliminates or reduces that zero’s impact. The only way to change your relationship to the zero is to change which version of roulette you are playing. A European wheel with one zero gives you half the edge of an American wheel with two zeros. A French wheel with la partage rules on even-money bets gives you the lowest edge available. This is a table selection decision, not a betting pattern decision.

What you should focus on instead of combinations that attempt to “beat” the edge is choosing a risk profile that suits your goals and your bankroll. If you have a modest budget and want to play for a while, outside bets with small stakes per spin give you more spins for your money and a gentler learning curve. If you have a larger bankroll and prefer the possibility of a large single hit, inside bets offer that at the cost of longer losing streaks. Neither is mathematically superior. The only thing you control is which version of the game you sit down to and how much you are willing to treat as entertainment expenditure rather than as an investment.

Remember that all of this assumes you are playing for real money. If you are learning the game, use free practice modes available at many venues to understand how the layout works and how different bet types feel without risking anything. Demo play is a learning tool, not a predictor of how your real-money session will go.

Before you sit down at any table, set a spending limit and a time limit. Decide what you are willing to lose before the session starts and treat that entire amount as the price of entertainment, not as money you expect to get back. If gambling stops feeling like entertainment, that is your signal to walk away. Players in most regulated markets have access to self-exclusion tools and deposit limits — use them if you find yourself chasing losses or increasing stakes beyond what you planned. The math is fixed; your relationship to it is yours to manage.

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