Probabilité implicite calculator: cotes to probability and overround
1win, licencié under Curaçao 8048/JAZ, offers 40 000+ sports marchés every day to over 400 000+ registered players. This probabilité implicite calculator converts any cotes format inpour gagner probability and calculates the overround (margin) built into a full marché. Use code promo XLBONUS when you register.
Probabilité implicite and overround calculator
Enter cotes for each outcome in your marché. Add as many outcomes as needed.
How this calculator works
Every set of betting cotes implies a probability. For cotes décimales, probabilité implicite = 1 / cotes, expressed as a percentage. For a decimal price of 2.50, the probabilité implicite is 40%. For American +200, the conversion is 100 / (200 + 100) = 33.33%.
When you sum the implied probabilities across all outcomes in a marché, you get a figure above 100%. This excess is called the overround, vig, or bookmaker margin. A 2-way marché where both sides are priced at 1.91 has an overround of (1/1.91 + 1/1.91) - 1 = 4.7%. The bookmaker expects to retain approximately 4.7 cents per dollar misered across a balanced book.
The fair (no-margin) probability for each outcome can be estimated by dividing the raw probabilité implicite by the sum of all implied probabilities. Par exemple, if Team A has a raw probabilité implicite of 55% and the total overround is 105%, the fair probability for Team A is 55/105 = 52.38%.
Lower overround means better value. A marché with 2% overround returns 98 cents per dollar on average; one with 10% overround returns only 90 cents. Comparing overrounds across bookmakers is a quick way to identify which offers the best price on a given marché.
The calculator supports any number of outcomes, making it useful for 2-way (résultat du match with no draw), 3-way (home/draw/away), and multi-outcome marchés like outright winners. The overround will naturally be higher for marchés with more outcomes because each additional pricing decision compounds margin.
This tool is also useful for detecting whether implied probabilities across a full marché are consistent (sum to a sensible overround). Wildly inconsistent marchés with very high overrounds (above 15%) should raise a red flag about marché efficiency or promotional pricing.
Why use it at 1win
1win prices 40 000+ marchés with competitive overrounds across football, tennis, basketball et bien plus. Claim code XLBONUS when you register to get started with a boosted balance.
FAQ
What is a good overround for a sports marché?
Premier football and tennis marchés at competitive bookmakers typically carry 2-5% overround. Marchés with 10%+ overround are generally poor value. Anything below 1.5% is exceptional.
How do I calculate probabilité implicite from cotes américaines?
For positive cotes américaines: probability = 100 / (cotes + 100). For negative: probability = |cotes| / (|cotes| + 100). So +150 implies 40% and -200 implies 66.67%.
What is the difference between implied and true probability?
Probabilité implicite is read directly from the bookmaker price and includes the overround. True (fair) probability divides probabilité implicite by the total overround to remove the margin.
Why does probabilité implicite sometimes exceed 100% across a marché?
The excess over 100% is the bookmaker's built-in margin. A 2-way marché summing to 105% means 5% overround; the book profits by 5% on average across a balanced book.
Can I use this for jeux de casino?
Oui. You can enter the cotes of any casino outcome to see its probabilité implicite and the avantage de la maison (equivalent to overround). Par exemple, a single number in European roulette pays 36:1 (decimal 37.00), implying 2.70% probability against a true 1-in-37 probability of 2.703%.