Implied probability

Implied probability is the conversion of betting odds into a percentage. It shows the expected probability of an outcome and is used by sports bettors to understand if the odds being offered by a bookmaker are good value or not.

Implied probability is important because it takes into account the bookmaker's margin.

How to calculate implied probability

Calculating implied probability is really simple but is slightly different depending on your preferred odds format.

Converting decimal odds to implied probability

In order to calculate implied probability using decimal odds, simply divide 1 by the decimal odds and multiple it by 100.

(1 / decimal odds) * 100 = implied probability

For example, if the odds for Manchester United to beat Chelsea at home were 1.50, the implied probability of the home win would be 66.7%.

(1 / 1.5) * 100 = 66.66%

Converting fractional odds to implied probability

To calculate implied probability using fractional odds, divide the denominator by the sum of the denominator + numerator, and then multiply by 100.

denominator / (denominator + numerator) * 100 = implied probability

For example, if the odds for Manchester United to beat Chelsea at home were 1/2, the implied probability of the home win would be 66.7%.

(1 / (1+2)) * 100 = 66.66%

Converting American odds to implied probability

If you use American odds then you will need to calculate negative and positive odds using slightly different formulas.

Negative odds

To calculate implied probability for negative American odds, divide the odds by the sum of the odds + 100 and then multiple by 100.

Negative American odds / (Negative American odds + 100) * 100 = implied probability

For example, if the odds for Manchester United to beat Chelsea at home were -200, the implied probability of the home win would be 66.7%.

200 / (200 + 100) * 100 = 66.66%

Positive odds

To calculate implied probability for positive American odds, divide 100 by the sum of the odds + 100 and multiply by 100.

100 / (positive American odds + 100) * 100 = implied probability

For example, if the odds for Chelsea to beat Manchester United away from home were 200, the implied probability of the away win would be 33.3%.

100 / (200 + 100) * 100 = 33.33%

How to use implied probability to improve your betting

Understanding implied probability is absolutely critical to becoming a long-term profitable sports bettor. Only by understanding the implied probability of betting odds are you able to understand if a bet represents value or not.

Simply put, if you're serious about making money from betting on sports then you should only ever place a bet if the expected probability of an outcome is greater than the implied probability of the betting odds.

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