Implied Probability
Convert American odds (moneyline) to implied probability percentage instantly. Free online betting odds calculator with decimal odds, fractional odds, and payout analysis.
About This Calculator
The Implied Probability Calculator converts American odds (moneyline odds) into an implied probability percentage, helping you understand the likelihood of an outcome as implied by the odds set by bookmakers. This free online tool is essential for sports bettors, traders, and anyone analyzing betting markets to make informed decisions.
The calculation uses two formulas depending on whether the odds are positive or negative. For positive odds (underdog), implied probability = 100 / (odds + 100). For negative odds (favorite), implied probability = odds / (odds + 100). The calculator also converts to decimal odds and fractional odds, and with an optional stake input, shows the gross return and net profit. The results include a probability breakdown chart (pie) and a payout breakdown chart (bar) for visual analysis.
Regional Notes
American odds (moneyline) are the standard betting format used in the United States and Canada. In the UK and Europe, fractional odds (e.g. 2/1) and decimal odds (e.g. 3.00) are more common. This calculator supports all three formats by converting from American odds. Bettors worldwide can use the implied probability to compare value across different odds formats and bookmakers. The calculator works with any currency — simply enter your stake and the results will display in the detected regional currency format.
Frequently Asked Questions
What is implied probability in betting?
Implied probability is the conversion of betting odds into a percentage that represents the likelihood of an outcome occurring according to the odds set by the bookmaker. For American odds, if the odds are positive (+200), the implied probability is 100 / (odds + 100). If the odds are negative (-150), the implied probability is odds / (odds + 100).
How do you calculate implied probability from American odds?
For positive American odds (e.g. +200): Implied Probability = 100 / (odds + 100). For negative American odds (e.g. -150): Implied Probability = odds / (odds + 100). Always enter the odds as a positive number and select the sign using the dropdown. For +200, implied probability = 100 / (200 + 100) = 33.33%. For -150, implied probability = 150 / (150 + 100) = 60%.
What is the difference between positive and negative American odds?
Positive American odds (e.g. +200) indicate how much profit you would make on a $100 bet. Negative American odds (e.g. -150) indicate how much you need to bet to win $100. Positive odds represent underdog outcomes (less likely), while negative odds represent favorite outcomes (more likely).
Can implied probability be over 100%?
Implied probability can exceed 100% in certain betting markets due to bookmaker margins or when combining multiple outcomes from the same event. For example, a -10000 favorite has an implied probability of approximately 99.01%, and extreme odds can push the total of all outcomes past 100%, which represents the bookmaker's overround or vigorish.
How do you convert implied probability to decimal odds?
To convert implied probability to decimal odds, use the formula: Decimal Odds = 1 / Implied Probability. For example, if the implied probability is 60% (0.60), the decimal odds would be 1 / 0.60 = 1.67. For positive American odds, decimal odds = 1 + (odds / 100). For negative odds, decimal odds = 1 + (100 / odds).
What is the formula for fractional odds from American odds?
Fractional odds are derived from the decimal odds minus one. First convert American odds to decimal odds. For positive odds (+200): decimal = 1 + (200/100) = 3.00, fractional = 2/1. For negative odds (-150): decimal = 1 + (100/150) = 1.67, fractional = 67/100 simplified to approximately 2/3.
How do bookmakers set odds and implied probability?
Bookmakers set odds by estimating the true probability of an outcome and then adding a margin (overround or vigorish) to ensure profitability. For instance, if a bookmaker estimates a 50% chance, they might offer odds implying 52% probability. The difference between the implied probability and the true probability represents the bookmaker's edge.
What is a good implied probability for betting?
A good implied probability depends on your own assessment of the true probability. If you believe an outcome has a 40% chance of occurring but the odds imply only 30%, there is positive expected value (+EV). Smart bettors look for discrepancies between implied probability and their own calculated probability to find value bets.