Overround and probability calculator

Instructions

  • The selection name column is optional and does not affect the calculation.
  • Press reset or type over the prefilled example odds.
  • The odds for all possible outcomes must be included.
Book %: 103.09%
Overround: 3.09%
Book %: 103.09%
Overround: 3.09%
Selection name
Probability
1
Must be a number greater than 1. Must be a fraction, for example 2/1. Must be "+" or "-" and a whole number over 100.
51.55%
2
Must be a number greater than 1. Must be a fraction, for example 2/1. Must be "+" or "-" and a whole number over 100.
51.55%
3
Must be a number greater than 1. Must be a fraction, for example 2/1. Must be "+" or "-" and a whole number over 100.

With the above calculator you can work out the book % and sportsbook’s overround for any betting market. This means you can check if a sportsbook is giving you good value odds and you can check whether arbitrage opportunities exist across different sportsbooks.

The overround calculator uses decimal odds, if you are not comfortable with decimal odds see our odds conversion table with probability.

How low should the overround be?

This table is for 2 selection betting markets, it is normal for the overround to rise as the number of possible betting selections rise because some overround has to be added to the odds of each selection.

OverroundValue
NegativeArbitrage bet on all selections for guaranteed profit!
0% – 3.5%Competitive good value odds
3.5% – 5%Acceptable odds
5%-7%Poor value odds, look elsewhere
Greater than 7%A rip off!

It is almost impossible to make long term profit if your sportsbook gives you odds with more than a 5% overround. See our best odds sportsbook rankings to find out if that is the case with your sportsbook.

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