The percentage behind the price
Implied Probability Calculator
Enter the odds for every outcome in a market to see the margin and the fair probabilities.
Transparent math
How it works
We use the proportional (multiplicative) method to remove the margin. It is the most common method and the one stated on our methodology page.
Read our methodology →Overround = Σ pᵢ · Margin = overround − 1
Fair pᵢ = pᵢ ÷ overround · Fair odds = 1 ÷ fair pᵢ
FAQ
Frequently asked questions
How do you calculate implied probability from odds?
Implied probability = 1 ÷ decimal odds. −110 is 1.91 in decimal, so the implied probability is 52.38%.
What is the vig (overround)?
Add up the implied probabilities of every outcome. A fair market totals 100%. Two sides at −110 total 104.76%, so the bookmaker’s margin (vig) is 4.76%.
How do you remove the vig?
Divide each implied probability by the total (proportional method). At −110/−110 each side becomes 50.00%, which is fair decimal odds of 2.00.
What about three-way markets like soccer 1X2?
Same method with three prices. Odds of 2.50 / 3.20 / 3.00 total 104.58% — a 4.58% margin. Fair probabilities: 38.25% / 29.88% / 31.87%.
What if the total is under 100%?
That happens when you combine the best prices from different bookmakers — for example 2.10 and 2.10 total 95.24%. It indicates an arbitrage opportunity, though limits and price changes make these rare in practice.
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