Enter the odds for every possible outcome to calculate the total implied probability and market overround.
| Outcome | Implied | Normalized |
|---|---|---|
| Enter market odds to see the breakdown. | ||
Overround shows how far the combined implied probabilities exceed 100%. It should not be interpreted as guaranteed bookmaker profit.
Betting odds can be converted into implied probabilities. In a perfectly fair market with no margin, the probabilities of every possible outcome would add up to exactly 100%.
Bookmaker prices usually add up to more than 100%. The amount above 100% is commonly called the overround.
It is one way of seeing how much margin has been built into the prices offered across the entire market.
First, convert every price in the market into implied probability.
Then add all of the implied probabilities together.
Imagine a two-outcome market where both sides are priced at decimal odds of 1.90.
The two implied probabilities add up to 105.26% rather than 100%. The extra 5.26 percentage points represent the market's overround.
The same calculation works when a market has three outcomes, such as a standard football 1-X-2 market.
The calculator is not limited to two-way markets. Add every possible outcome and it will calculate the overround across the complete market.
The calculator also displays a normalized probability for every outcome.
This takes the market's implied probabilities and scales them back so that they add up to 100%.
This is useful for seeing how the market's probability is distributed after removing the overround proportionally.
It is still only a mathematical normalization of the prices. It should not automatically be treated as the true probability of an outcome.
A market with a 5% overround does not mean the bookmaker will automatically make exactly 5% profit from all bets placed on that market.
Actual bookmaker results depend on how money is distributed across the different outcomes, how prices move, liabilities, promotions and many other factors.
Overround is best understood as a property of the prices being offered, not as a guaranteed accounting result.
All else being equal, a lower overround means less margin has been built into the combined prices of the market.
That can make the market mathematically more competitive for the bettor, but overround alone does not tell you whether an individual selection is correctly priced.
A bookmaker can have a relatively low overall market margin while one individual outcome is still priced very differently from your own assessment.
Looking only at individual odds can hide what is happening across the complete market.
By converting every outcome into probability and adding them together, you can see how much the market exceeds the 100% baseline.
This makes it easier to compare different betting markets, understand bookmaker pricing and see the mathematical relationship between odds, probability and overround.