Casino Guide: How to Calculate Odds

Knowing how to calculate odds is fundamental for any casino goer looking to improve their chances of winning, whether they’re a complete novice or an experienced player. If you can learn how to calculate odds you can make informed decisions about your betting strategy, increase the durability of your bankroll, and remain at the table long enough to (hopefully!) turn a profit.

If you’ve ever wanted betting odds explained, this in-depth guide is the place to go! We’ll walk you through the basic of how to calculate odds – with some examples in popular casino games. Then, once you’re in the know about the different bets and your chances of walking away a winner, you’ll be ready to take on the house!

Betting Odds Explained

In essence, when you calculate odds, you’re attempting to accurately predict how likely it is that an event will happen versus how unlikely it is. In a betting environment, if your prediction is correct, you’ll win money. Betting odds are usually presented in one of three ways, as either a fraction, a percentage, or a decimal – though the latter is normally reserved for sports betting returns. Thankfully, you don’t need to be an ace mathematician

Calculate Odds – Fractions

Fractional odds are probably to most common when assessing the chances of winning in the casino, primarily because they are easy to identify and understand. In addition, they give you a clear indication of your betting returns.

Examples of fractional odds may be 20/1, 9/2, 2/1, and so on. In this format, you can calculate odds by comparing the first number with the second number – if the odds are 20/1, you’re 20 times more likely to lose than to win. If you throw a six-sided die and are asked to guess which number will come up, your odds are 6/1. If you’re asked to guess two numbers, your odds become 6/2. The convenient part of learning how to calculate odds with fractions is that they can be simplified, so 6/2 would become 3/1, making it easier to understand your chances.

On top of this, fractional odds help you calculate your betting returns. If your odds are 10/1 and you place a £5 bet, you stand to win £50 if your bet comes through, plus the return of your stake.  

Calculate Probability

Converting fractional odds to percentages can be a great way of understanding your chances of winning. This is done in an easy formula: Percentage = B / (A+B). While this may seem complicated and unnecessary, the actual process is simple and is an effective way of contexualising your probability. In the formula, A and B represent the first and second numbers that make up your fractional odds – with 10/1 odds, 10 would be ‘A’ and one would be ‘B’!

If you were to calculate odds, 10/1 for instance, the formula would be 1 / (10+1) = 0.09. This means that at 10/1 odds, your probability of winning is 9%. If you had fractional odds of 16/3, to provide another example, you could put that into the existing formula and have 3 / (16+3). If calculated correctly, the probability of you winning this wager would be 15.8%. 
The only downside to using percentages to calculate your odds is that there is little to no indication of your potential betting returns.

Calculate Odds as Decimals

Decimals are becoming a prevalent way to calculate odds, though this does mostly apply to sportsbooks rather than casinos. As with fractions or percentages, the bigger the decimal odds, the less likely it is that the event will happen. The main advantage of decimal odds is that you can easily work out your betting returns regardless of your stake.

Again, there is a simple mathematic equation to calculate your potential betting returns: Winnings = (Odds x Stake) – Stake. Let’s explore an example of decimal odds in action:

If you correctly calculate odds, you can see that your potential returns would be £45!

How to Calculate Your Odds in the Casino

Now that you’ve learned how to calculate odds, let’s apply some of these rules to an actual casino game – specifically roulette.
One of the easiest and most risk-free bets you can make on a roulette table is red or black. On a European roulette table, there are 37 separate pockets: 18 red, 18 black, and a green zero pocket. So, if you bet on red, for example, your fractional odds would be 18/37. If you calculate your odds, the probability that red will come up is 48.6% as the single green tips the advantage to the house.

Alternatively, if you bet on a single number your odds of winning would be 1/37. In this scenario, the probability that you’d win your bet is just 2.7%, with a 35:1 payout. This means that if you bet £5 on a single number and won, your payout would be £180 in total!

It’s important to understand that every casino game carries different odds and each way of calculating odds may not apply. However, with a firm knowledge of how to calculate odds, you can start to apply the methods in any casino game or betting environment of your choice.

Now that you’ve had betting odds explained to you in detail, why not try out an online roulette, blackjack or baccarat game to put your new knowledge into practice!