Roulette is a well-known casino game, but the way individual bets work can feel confusing at first.
This guide focuses on the straight up bet, where a single number is chosen. It explains how it works, the odds and payout, and how those change between European and American wheels, with clear examples.
You will also see how probability, expected value and the house edge fit together, plus a quick reference table and a look at common myths.
Read on to learn more.
What Is A Straight Up Bet In Roulette?
A straight up bet in roulette is a wager placed on a single number on the table, such as 7, 23, or 0. Only one number is chosen and covered by placing a chip directly on top of it.
This type of bet may be placed on any of the main numbers, including zero (and double zero on American tables). It does not cover groups of numbers or outside sections such as red/black, odd/even, or high/low.
Players who choose a straight up bet will only win if the ball lands exactly on their chosen number after the wheel is spun. All other outcomes do not result in a win for this bet.
So how often does that single number land?
What Are The Odds Of Hitting A Single Number?
The odds of a straight up bet depend on the wheel. In European roulette, there are 37 pockets (numbers 1 to 36 plus a single zero). In American roulette, there are 38 pockets (numbers 1 to 36, a single zero, and a double zero).
If a player backs one number, the chance of it landing is 1 in 37 on a European wheel and 1 in 38 on an American wheel. That is about 2.70% for European roulette and about 2.63% for American roulette.
Each spin is independent of the last. Previous results do not influence the chance of a number landing next.
With the chance in mind, the natural next question is what a winning spin actually pays.
How Much Does A Straight Up Bet Pay?
A straight up bet in roulette pays 35 to 1. If a player wagers £1 on a single number and it wins, they receive £35 in winnings plus their original £1 stake back, for a total return of £36.
The payout ratio is the same on both European and American wheels. The amount collected simply scales with the size of the stake placed on the winning number.
Those figures are fixed, but the wheel layout still changes how often a win occurs.
European Versus American Roulette: Single Number Differences
European and American roulette wheels have key differences that affect single number bets.
The European wheel features 37 pockets, which include numbers 1 to 36 and a single zero. The American wheel contains 38 pockets: numbers 1 to 36, one zero, and an additional double zero.
This extra pocket on the American wheel reduces the chance of any individual number landing on a given spin. The payout for a straight up bet stays the same on both wheels, so the lower probability on the American layout leads to a higher overall cost of play over time.
If you want to see how the numbers are worked out, the next section breaks the calculation into simple parts.
How Do You Calculate Probability And Payout For One Spin?
Calculating the probability and payout for a straight up bet helps show how roulette is structured. These figures describe the game’s design rather than forecast what will happen next.
Example Calculation With European And American Wheels
For probability, the total number of pockets on the wheel matters. In European roulette there are 37 pockets. The probability of a chosen number landing is 1 divided by 37, which is about 0.027 or 2.70%.
In American roulette there are 38 pockets. The probability is 1 divided by 38, which works out to about 0.026 or 2.63%.
The payout for a straight up bet is fixed at 35 to 1. If a player places a £1 bet and their number wins, they collect £35 in winnings plus the original £1 stake, making a total return of £36.
These calculations reflect the same point made earlier: each spin has the same probabilities, regardless of what happened before.
With the basic maths clear, it becomes easier to see what that means on average over many spins.
How Do You Work Out Expected Value For A Single Number Bet?
Expected value shows the average amount a player may win or lose per straight up bet over the long run. It weighs each outcome by its probability.
To find the expected value for a single number bet, consider both the chance of winning and the size of the win or loss. In European roulette, there is a 1 in 37 chance of winning £35 net, and a 36 in 37 chance of losing the £1 stake. Using the formula:
(Expected gain × Probability of winning) + (Loss × Probability of losing)
For a £1 stake in European roulette:
(£35 × 1/37) + (–£1 × 36/37) = £0.95 – £0.97 = –£0.02
So, on average, a player may lose around 2p per £1 bet over many spins on a European wheel. On an American wheel the expected value is lower, at about –£0.0526 per £1, because of the extra double zero.
This average does not predict short-term results, but it does explain the consistent gap between what is paid out and what is staked.
How Does The House Edge Affect Straight Up Bets?
The house edge is the built-in advantage that casinos hold over the player. It appears in every roulette bet, including straight up bets.
For European roulette, the house edge is about 2.7%. There are 37 pockets, but the 35 to 1 payout is set as if only 36 outcomes were in play.
On the American wheel, which has 38 pockets due to the extra double zero, the house edge increases to about 5.26%. The payout still covers only 35 other numbers, so the additional pocket raises the casino’s advantage.
The edge does not change the randomness of any single spin, as explained earlier. It simply reflects how the payouts are calibrated over time.
With that in mind, it is easy to see why a few common ideas about single number bets do not hold up.
Common Myths About Single Number Bets Debunked
Several misunderstandings surround straight up bets in roulette. Clearing them up helps keep expectations realistic.
One myth is that certain numbers are "due" because they have not appeared in a while. Each spin is independent, so previous outcomes do not affect what happens next.
Another belief is that staking on more than one single number at once increases the chance of making an overall profit. It does cover more possible results, but it also involves placing more stakes, and it does not change the house edge that applies to each wager.
Some think that changing bet amounts or patterns will influence the outcome. The result of every spin is random and not affected by past or future bets.
There is also a view that one wheel or table is more "fair" than another. Licensed casinos are required to meet strict standards so roulette wheels produce random outcomes.
If gambling starts to affect your well-being or your finances, seek support early. Independent organisations such as GamCare and GambleAware offer free, confidential help for anyone who needs it. That way, the numbers above stay useful as information, not pressure to play.
**The information provided in this blog is intended for educational purposes and should not be construed as betting advice or a guarantee of success. Always gamble responsibly.