Understanding the Mathematics Behind Online Casino Odds

Understanding the Mathematics Behind Online Casino Odds

In order to be good at something, you first need to understand it, right? Well, that’s also the casino with online casino odds. The more you understand how the system works, the better chances you’d have to win some money.

People have always wanted to know the cheat code or the system that will help them win every hand at a casino. Sadly, such a thing doesn’t exist.

However, you can calculate the probability of odds, and tailor your gameplay to increase your winning chances.

The house edge

In order to understand how odds work, you first need to understand the house edge. This is a term used in common practice that refers to the advantage that the casino has over the players in every game.

Do you know the phrase “The house always wins”? Well, that’s because every casino game has a house edge ensuring they come out profitable.

The math behind the edge

Imagine a roulette wheel with 38 numbers (1-36, 0, and 00). If you bet on a single number and win, the payout is 35 to 1. However, the true odds are 37 to 1 because there are 37 losing numbers and only 1 winning number. This disparity creates the house edge.

Let's delve into some numbers to see which casino game has the best house edge. In American roulette, the house edge is around 5.26% due to the presence of the extra 00 slot.

European roulette, with only one 0, lowers the house edge to approximately 2.7% meaning that you’ll have more winning chances.

But the house edge is calculated over a long period and you cannot know exactly when the casino will return the money to players or keep them.

Probability and payouts

The next important thing for understanding the odds is looking at probability. When you play games like Blackjack or Poker where the outcome is not based solely on luck, understanding probability can be a real game-changer.

Basically, probability is the mathematical concept that will tell you the likelihood of an event happening. In casino games, probabilities determine your chances of winning or losing.

👀 For example, in a game of roulette, the probability of the ball landing on a specific number depends on the wheel's design and the number of pockets.

Calculating probability is quite simple. You just have to divide the number of favourable events by the total number of possible events.


Slots are one of the most popular casino games, often taking centerstage at casinos like OC88. Why? Well, because they offer entertaining gameplay and huge prizes.

For more information on OC88 Casino, check out the link below: oc88.com

With slot games, the situation is a bit different, and you cannot really calculate the probability of an event since there are many different combinations. But one thing is for sure.

The chances of hitting a jackpot are often in millions to one, and yet most people hope that they’ll get lucky.

👉 Modern slots use something called Random Number Generator to ensure fairness and the unpredictable nature of the games.

The only number that you can look at when playing slots is the Return to Player (RTP) which is the opposite of the House Edge. For example, if the house edge is 2%, the RTP will be 98%. Playing a slot with a higher RTP might give you better winning chances and more frequent payouts.

The role of random number generators (RNGs)

Random Number Generators is a software with sophisticated algorithms that ensures that every outcome is totally random and unpredictable. Therefore, calculating the odds or probability isn’t possible.

This randomness is crucial for creating fair and unbiased outcomes in casino games, replicating the unpredictability of real-world casino environments.


With Blackjack, you can calculate the probability of certain favourable events, and even use strategies that can help boost your winning chance. But it all depends on the number of decks used and the rules of play.

For example, it is quite easy to calculate the probability of a single-deck Blackjack game, and the house edge comes even below 1%. That’s why most casinos use 4 or 8 deck of cards when organizing a game.


One aspect often overlooked is variance, which adds spice to the casino experience. Variance refers to the ups and downs of short-term luck, affecting both players and casinos.

  • High Variance Games: Think of high-risk, high-reward games like some slots or certain types of poker tournaments. These games can lead to massive wins or losses in a short period, making them thrilling yet unpredictable.
  • Low Variance Games: On the other end are games like baccarat or even-money bets in roulette. Whilst they may not offer sky-high payouts, they provide a more stable, less volatile experience.

Strategies and myths for getting better odds

In the world of online casinos, strategies abound, from card counting in blackjack to progressive betting systems. But do these strategies hold water?

  • Card Counting: Popularised in movies like “21,” card counting involves keeping track of high and low cards in blackjack. Whilst it can shift the odds in the player's favor, casinos have countermeasures like reshuffling decks or using multiple decks to thwart this strategy.
  • Betting Systems: From the Martingale to the Fibonacci sequence, betting systems claim to beat the odds. However, they often overlook the limits of bankrolls and the reality of losing streaks.
Receive bonuses and promos direct to your inbox

Click here

games slots