Is roulette wheel bias still a “thing”?

For many years, roulette wheel bias was the scourge of online slots casinos and players alike. A biased wheel could give either the casino or the player an advance if one side or the other had correctly identified the bias.

Today, most people play casino games at online casinos where the roulette wheels are part of gaming machines with regulation Random Number Generators that determine the results of a spin.  Land-based casinos also rely on technology, though the technology involves ensuring that the three-dimensional roulette wheel itself is fair and accurate.

Skeptics point out that, for centuries, casinos have been promising that their wheels’ accuracy is above doubt and that there is no cheating possible.  Yet time after time, a roulette wheel bias has been detected and someone on one side or another of the table was able to take advantage.

So what is the status of a possible biased roulette wheel in 2020?     


Roulette wheel bias occurs when specific numbers on a roulette wheel come up more than they should. The bias is caused by a defect in the wheel defects. Some players think that they can “beat the wheel” by analyzing a series of spins, noting which numbers come up the most and then betting on those numbers.  Sometimes that works but sometimes it doesn’t.

There are many ways for a wheel to develop a bias. One way that a wheel can develop a bias is when, over time, the glue on a colored plastic glued to the pocket loosens. Then the plastic is raised so when the ball hits one of those pockets the ball bounces less than it normally would (called “deadening”). It comes to rest in specific areas of the wheel more frequently than it would if spins were completely random.

In addition to the example given above (“pocket bias”) there’s also section bias where the ball favors specific wheel sectors and dynamic bias that is present for only a few hundred spins at a time (making it very hard to check for such a bias). 

Bias can occur when a wheel suffers wear and tear. That means that it’s not as random as it’s supposed to be and can result in deformed balls, unequal pocket sizes, loose frets or a shaky wheel shaft. Roulette can be beaten through wheel bias so casinos are very careful to make sure that the roulette table has an unbiased wheel.  Even with today’s technology however, you might still find a wheel that shows bias. 

Spotting a Biased Wheel

Some people claim that you can spot a wheel that has imperfections with patience and some basic math. Once you find, what you think, is an imperfection, you need to record results for a period of time. The amount of data you need depends on whether you’re looking for bias towards specific sections or pockets. Section bias doesn’t require as much data because it’s easier to spot a biased section than single pockets.

If you want to identify a biased wheel you should start by:

  • tracking 1,000 spins.
  • put the data into a spreadsheet.
  • check to see whether a section of 10 numbers between 27 and 6 is biased.

To see if specific pockets are off you need to analyze the wheel for a longer period of time. You might need anywhere between 5,000 and 10,000 spins’ worth of data to identify pocket bias.


Biased roulette wheels were more common in the past when the technology to secure roulette wheels wasn’t yet used. In

In the past there have been cases of gamers who made millions through identifying a wheel bias and then manipulating the game.  In the late 1800s Joseph Jagger identified and exploited biases in the wheels of the roulette tables of Monte Carlo.  He made a £65,000 profit (£7 million in today’s currency) by taking advantage of a biased wheel at the Beaux-Arts Casino. When the casino switched around the wheels it threw him off and he left but took his winnings with him.

In the 1990s Gonzalo Garcia-Pelayo  found biased wheels at Las Vegas and Spanish casinos.  The combination netted him €1.5 million in winnings.

New Wheels and Casino Strategies

Today most casinos use the Starburst model roulette wheels. Starburst wheels feature shallower pockets and metal wheels which are designed to eliminate two of the main sources of wheel bias.

In addition it is customary for casinos to run regular inspections on roulette wheels to ensure their proper operation.  Staff members examine the entire wheel including the wheel shaft, balls, pockets, frets.

Finally, results are electronically monitored to alert the casino if anything is mathematically out of place.

But experts admit that wheel bias is still possible to some extent. Any of these elements can result in a biased roulette wheel:

  • Bent frets
  • Deformed balls
  • Deformed ball track
  • Flawed wheel shaft
  • Older wheels