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Casino Probability: Why Do Casinos Always Win?

Recently updated on May 30th, 2020

Whether you’re a regular player or a beginner, you’ve probably wondered: “why do casinos always win?” And, the answer might just surprise you because they don’t win every time. There’s just a built-in edge on all gambling games that makes the casino a profit. This is known as the house advantage or edge.

This advantage is what allows casinos to make a profit and keep the doors open. Even online casinos have an edge, but it’s built into the games. This varies from game to game and from casino to casino. So, let’s look at the probabilities.

Why Do Casinos Always Win?

Why Do Casinos Always Win: House Edge

In every game of chance, the casino has to make profits to be able to payout wins. So, the industry came up with a way to alter the odds in its favor. Every game has the starting chances, and the casino adds a few extra as a percentage to every outcome.

That way, it gets a piece of your bet back, whether you win or not. And yes, this is perfectly legal for licensed websites and venues. Here’s an example using roulette:

  • Generally, the odds of winning on a specific number are 37 to 1.
  • But, the casino pays out only 35 to 1.
  • So, it keeps 2.7% even if you win.

Thus, the casino will eventually never lose too much, and you can keep visiting.

Return-to-Player Percentage

Usually, the casino games house edge is expected for table games, but did you know that slots also have an advantage? Factored into every spin is a 10% probability that you won’t win factored into the return-to-player percentage (RTP).

Also, some land-based casinos will remove buttons on slot machines to increase profits. However, this is illegal in many jurisdictions. On an average slot, the advantage would be:

  • An average RTP of 96% for a winning spin.
  • Odds on a big win are hard to calculate. But, if you win at least 100 coins, the casino keeps 4.

And so, that should answer the question: “why do casinos always win?”.

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