How to use the calculator
- The “Selection name” column is optional and does not affect the calculation.
- Choose your preferred odds format; decimal, fractional or American.
- 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 | 51.55% | ||
| 2 | 51.55% | ||
| 3 |
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.
How much overround should there be?
The below table is for 2 selection betting markets. It’s normal for the overround to rise as the number of selections rise, because some overround has to be added to the odds of each selection.
| Overround | Value |
|---|---|
| Negative | Arbitrage 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.