Esports Betting Odds & Implied Probability Explained

Odds are at the heart of all betting markets, and you won’t get far in the world of esports betting if you don’t understand how they work, and how they are related to probabilities. For those who are new to esports betting, or those who need a refresher, we’ve put together this guide to one of the most important aspects of betting, telling you how to use the three main esports betting odds formats: fractional, american and decimal.

Implied Probability

When you’re betting on esports, the odds on your favourite sports betting site will give you two pieces of information. They will tell you the size of your winnings if your bet is successful (we will cover that in the following sections) and they are also expressions of probability.

So, for example, if you see that Astralis are rated at 2/1 to win a CS:GO tournament, this equates as 0.33 in probability terms. Effectively, the bookmaker is saying that Astralis have a 33% chance of winning the tournament. Looking at odds in this way can be useful as it encourages you to think about relative winning chances rather than just thinking about your potential bet returns.

It is simple to translate odds into probability. There are plenty of online calculators that can help, but you can also do it yourself, though the calculation is slightly different depending on the odds format.

For example, to turn fractional odds into a probability figure, you simply divide the second number into the total of both numbers. So, in the case of odds of 2/1, the calculation is:

2/1 = 1/(2+1) = 1/3 = 0.3333

To turn the probability into a percentage, you simply multiply it by 100:

0.3333 * 100 = 33.33%

When you’re looking at esports betting odds, it is important to remember that when a bookmaker quotes a price of 2/1, that doesn’t necessarily mean that they think that contender has a 33% chance. Bookmakers’ odds are influenced by a number of factors, including the weight of bets they have taken on each selection, and, most importantly, their profit margin.

Bookmakers ensure a profit by offering odds that, when turned into probabilities and totalled, add up to more than 1.0 or 100%. You can work out the extent of a bookmaker’s profit margin on a particular market by translating all of the odds into probabilities or percentages and totalling them.

For example, let’s say a CS:GO tournament is at the semi-final stage and your chosen sportsbook is offering these odds on the remaining four contestants:

Astralis – 7/4

Liquid – 2/1

FaZe – 4/1

Vitality – 5/1

To calculate the probability for each set of odds, use the formula from above to give the following:

Astralis – 36.36%

Liquid – 33.33%

FaZe – 20.00%

Vitality – 16.67%

Adding up all of the probabilities in this market gives us a total of 106.36, which means that the bookmaker margin here is 106.36% – 100% = 6%. The higher the bookmaker margin, the harder it is for the esports punter to find an edge, so look for markets with margins as close to zero as possible.

Fractional Odds Explained

We’ve already seen how to use fractional odds to calculate probability, but you will also need to know how to use the odds to work out your potential winnings if your bet is successful.

With fractional odds, it is important to remember that the odds don’t take account of your stake, which will be returned to you when you win. For example, if you bet $10 on FaZe to beat Liquid at 2/1, your profit will be calculated by dividing the first figure by the second and multiplying by the stake:

$10 stake x (2/1) = $10 x 2 = $20 profit.

But your actual returns will also include your $10 stake, so your online sports betting account will be credited with $30 if this bet is a winner.

Decimal Odds Explained

Fractional odds are the traditional form of odds used in the UK and Ireland betting sector, but in Europe, and on UK betting exchanges, it is common to see decimal odds.

Like fractional odds, decimal odds can show both the return on a winning bet and the probability of that bet being successful. Calculating probability from decimal odds is simple and involves dividing the decimal odds into 1 (to find probability) or 100% (to find probability percentage). For instance, decimal odds of 4.0 represent a probability of 0.25 or 25%

1 / 4.0 = 0.25 or 100% / 4.0 = 25%

Calculating your potential winnings using decimal odds is the same calculation that you use with fractional odds, only this time, the result includes your stake. If you bet $10 on Astralis to beat Liquid at decimal odds of 3.0, this is the calculation:

$10 stake x 3.0 = $10 x 3 = $30 return.

American Odds Explained

There is another form of odds that you might come across when betting on esports. American odds are significantly different to the other two forms discussed above. American odds are sometimes called Moneyline Odds and a typical esports match betting market might look like this:

FaZe – 200

Liquid + 150

With American odds, the two figures represent different propositions. In the case of the minus figure, which is always associated with the favourite, the number represents the amount of money you would need to bet in order to win $100. The plus figure, meanwhile, represents the potential return on a bet of $100. This is how you work out the probability of the odds on FaZe quoted above:

(First remove the minus symbol)

Probability = Odds / (Odds + $100)

= 200 / (200+100)

= 200/300

= 0.667 or 66.7%

To work out the probability for Liquid in the above market, the equation is slightly different:

Probability = $100 / (Odds + $100)

= 100 / (150 + 100)

= 100 / 250

= 0.4 or 40%

Working out your potential winnings using American odds again requires slightly different calculations according to whether you are betting on the favourite. For at $10 bet on the favourite in this market:

(First remove the minus symbol)

Winnings = 100 / Odds * stake

= (100 / 200) * $10

= 0.5 * $10

= $5

And if you had a $10 bet on Liquid at odds of +150, the calculation would be:

Winnings = Odds / 100 * stake

= (150 /100) * $10

= 1.5 * $10

= $15.

In both cases, when you are calculating your winnings using American odds, the final figure will not include your stake, which will be added to your return.

Some of these calculations may appear fiddly, but they will soon become second nature, and if you get stuck, there are plenty of online calculators that can help.