Roulette Strategy

Any discussion of roulette strategy must begin with some observations about the mathematics behind the game. And the math behind roulette is straightforward. I’ll explain why later on this page, but the least you need to know is that roulette can’t be beaten in the long run with any kind of strategy.

All of the bets on an American roulette game offer the same house edge (5.26%) except for one, and that bet (the five-number bet), is even worse. It offers a house edge of 7.29%.

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The House Edge

The house edge is a percentage that predicts how much of each bet the casino expects to win over the long run. The formula is based on calculating the expected value of each bet.

To calculate the expectation, you look at the probability of winning versus the probability of winning, multiplied by the amounts won or lost.

For example, on a standard even or odd bet, you have a 18/38 chance of winning and a 20/38 chance of losing. If you’re betting a dollar, you’ll win $1 less than half the time and lose a dollar more than half the time. You have a 47.37% chance of winning a dollar, which equates to + $0.47, and a 52.63% chance of losing a dollar, which equates to -$0.53. When you add those together, you get an expected value of -$0.05, or 5.26%.


In Atlantic City and some other areas, a rule for “surrendering” is in place. This rule reduces the house edge, but it doesn’t eliminate it. It also only applies to the outside bets that pay even money. These bets include:

  • Red or black.
  • Odd of even.
  • High or low.

With the surrender rule in place, you only lose half your bet if the ball lands on 0 or 00. This reduces the house edge to 2.63%.

European Roulette

The European roulette table has a major difference from the American roulette table. The European version of the wheel only has a single zero, instead of 0 and 00. That’s why European roulette is also often called “single zero roulette”. This variation almost cuts the house edge in half again, to 2.7%.

Mathematically speaking, you’re still almost guaranteed to lose money, but you’ll lose it more slowly.

En Prison

In Europe, they not only offer a single zero roulette wheel, but they also offer a rules variation called “en prison”, which is similar to the “surrender” rule in Atlantic City. If you make an even-money bet and the ball lands on 0, your money is “imprisoned” instead of being lost.

On the next spin, if your original bet is good, then you get your original wager back. On the other hand, if your original bet loses, you lose your original wager.

This further cuts the house edge in half, to 1.35%, which makes single zero roulette with the en prison roulette a bet on par (almost) with blackjack and video poker.

Betting Systems

Multiple con-men and voodoo priests are eager to sell you roulette betting systems. These are all equally worthless, so you should never pay money for a “winning roulette system”. After all, since it won’t work, you might as well use one of the many free systems that are available.

These betting systems all involve variations of raising and/or lowering your wagers based on what happened on your previous bet. For example, when you’re using the Martingale System (one of the most popular roulette systems), you will double your bet after every loss until you get ahead.

Here’s how the Martingale works in actual play. You bet $5 on black. You lose. You bet $10 on black again, and you lose again. So now you bet $20 on black. This time you win. You gain back the $15 you lost on the two previous bets, and you’re $5 ahead for the session.

At first glance, this seems like a “can’t-lose” system, but that’s not how it works in reality. Two things prevent the Martingale from being a winning system:

  1. Betting limits
  2. Limited bankrolls

If you keep doubling your bets, you’ll hit the table limits faster than you might think. Look at the progression below:

$5 – $10 – $20 – $40 – $80 – $160 – $320 – $640

Most roulette tables accepting a $5 bet have a maximum bet of $500. Once you’ve lost seven times in a row, you’re unable to continue your progression because of the betting limits.

Even if you could continue, this still wouldn’t be a workable system, because eventually you’d go on a losing streak that requires bets beyond what your bankroll could cover. In the progression above, you will have lost $1275, so your next bet will have to be $1280. Even if you win at that point, you’re only ahead by $5.

And your chances of winning on that ninth spin are still only 47.37%. Each spin of the roulette wheel has the same odds of winning or losing as every other. The table has no memory of what happened on previous bets.

Biased Wheels

You’ll occasionally see people talk about exploiting biased wheels. The idea is that a roulette wheel is an object, and it’s not perfectly made, so some numbers will come up more often than others.

If you can “clock” the wheel and figure out which numbers come up more often, you supposedly can get an edge over the casino. There are a couple of problems with this “strategy”.

The first is that if you’re going to have any kind of statistical accuracy, you’ll have to record the results of at least 2000 spins. Most roulette tables only make 40 spins an hour, so you’d have to track results for at least 50 hours. Even after doing all that work, you might discover that the wheel isn’t actually biased, so you have to start all over again.

Even if the wheel does display a bias, it might not be significant enough to account for the house edge. Systems sellers will tell you that you can get meaningful information from 100 spins or fewer, but that’s mathematical nonsense.

Tracking the Dealer

Some people think that the dealer will consistently release the ball into the wheel at the same speed every time, out of habit. They then think they can predict where the ball will land, at least within a few numbers.

But this isn’t practical. Not only do you have to estimate how fast the dealer spins the ball, you also have to estimate how fast the dealer spins the wheel. Accounting for the bouncing of the ball caused by the dividers, you’re going to be facing a lot of randomness. Thinking that this is a winning roulette strategy is flat-out wishful thinking.

The best strategy for roulette is to expect to lose. Enjoy the relaxing and social nature of the game, and be sure to get a free drink from the cocktail waitress. Have fun betting on numbers that are significant to you, like your date-of-birth, but don’t fall into the trap of thinking that those “lucky numbers” will help you win in the long run, because they won’t. But you’ll have fun.