Free, no signup. Last updated 15 August 2026.
Enter every price in one market, both sides of a match or all three football outcomes. The calculator shows what each price implies, how much the probabilities exceed 100 percent, and what the fair prices would be with that margin removed.
In a fair market the chances of every possible outcome add up to exactly 100 percent. Bookmakers price them so the total comes out higher, and that excess is their margin: the overround, also called the vig or the juice. It is the cost of placing the bet, and it is charged whether you win or lose.
A two-way market priced at 1.91 on both sides implies 52.4 percent each, or 104.8 percent in total, so the margin is 4.8 percent. Strip the margin out proportionally and the fair price on each side is 2.00. Any bet you place is really a bet that the true probability is better than the marked-up price, not better than the fair one.
Implied probability is the chance of an outcome according to the odds, calculated as 1 divided by the decimal price. Odds of 2.00 imply 50 percent, odds of 1.60 imply 62.5 percent, and odds of 4.00 imply 25 percent.
The overround is the amount by which the implied probabilities of every outcome in a market exceed 100 percent. It is the bookmaker built-in profit margin, and a typical mainstream football market carries between 3 and 6 percent.
Add up the implied probabilities of every outcome, then divide each one by that total to rescale them back to 100 percent. Inverting the rescaled probability gives the fair price. This calculator does it automatically once you enter at least two prices.
Not within one bookmaker, but yes across several. When you combine the best available price for each outcome from different books, the total can fall below 100 percent, which is an arbitrage.
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