Probability

In order to understand betting odds firstly we need to understand probability.

Probability is the measure of the likelihood that an event will happen. Probability is quantified as a number between 0 and 1 (where 0 indicates impossibility and 1 indicates certainty). The higher the probability of an event, the more certain that the event will happen.

• Lets toss a coin

Since the coin is unbiased, the two outcomes have the same probability; the probability of “head” is the same as of “tail.” Since there are only 2 outcomes possible, the probability is 1/2, for each “head” or “tail”. Which means, the probability of “head” is 1 out of 2 possibilities and the probability of “tail” is also 1 out of 2 possibilities, expressed as 0.5 when converted to decimal, with the above-mentioned quantification system.

Decimal Odds

Decimal odds are another way expressing probability. Decimal odds express inverted probability, and that is why it is easy to calculate.

When we say it has a probability of Z% now Z is a number and not a percentage.

It is done by dividing 100% by probability.

For example, If Manchester United has a probability of 40% to win the match in decimal it would be like:
100% / 40% = 2.5

This is the decimal odd or also known as European odds.

So if you bet  X GBP with odds 2.5 you will get X*2.5 in case you win and if you subtract X GBP amount that you invested you will have 1.5 profit.

Fractional Odds

Another way to express odds are fractional odds.

If we would like to express the 2.5 decimal odd as fractional it would be 6/4 or 3/2 or 1.5/1

Be careful to not mistake as 2.5/1, as this would be your total return and fractional odds express only your profit without your stake.

To convert Fractional odds on Decimal odds simply divide numbers and add +1

6 divided by 4 = 1.5+1 = 2.5