How to convert odds in probabilities?

The articles: “The odds of a bookmaker can vary?” and “How many types of odds exist?” can help to better understand how odds work. In this article we’re going to explain how you can convert odds in probabilities.

It is very important to understand before you start calculating odds probabilities:

– The odd is the inverse of the probability.

– A bet is of value if the odd offered by the bookmakers is higher than the probability of the event in question.

Let’s consider the following example:

Inter vs Leverkusen

Since it is a neutral and eliminatory match, we may not consider the home and away factor statistics, including the overall statistics of the two teams in competitions. So:

Goal: Calculation of “More than 0.5 goals in the first half” odd:

In the last 10 games of the two teams, for Inter there were 9 games with “More than 0.5 goals in the first half” and there was only one in which was 0-0 at halftime. For Leverkusen, there were only 7 games with “More than 0.5 goals in the first half” and there were only 3 games with 0-0 at halftime.

So: (9+7) – 4 / (9+7) = 0,75 x 100 = 75%

Note: The result is always in decimal format but if we multiply by 100, we will get the % (the percentage).

So the fair odd for the market “More than 0.5 goals in the first part” is 1/0.75 = 1.33.

So, if in 20 games between the two teams we get 16 games in which there is at least 1 goal until the half time, then:

 16 x (1.33-1) – 4 = 1,28

That is, if we bet that there will be at least 1 goal until the half time at this odd 1.33, we will get 1.28 or 128% profitability in 20 bets.

The odd that the bookmakers offer to the market “More than 0.5 goals in the first half” is 1.31 and the main goal is to know if this odd is fair.

So,

16 x (1.31-1) – 4 = 0.96, we will get a 96% return on 20 bets. In this case as the profitability is lower (128% > 96%), the bet will not be of value. It will only be of value if they offer an odd higher than 1.33, because the prize offered will be higher than the probability of losing.