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Convert American, decimal, or fractional odds to the implied win probability - and see your payout for any bet.
Convert any odds to implied win probability - and see your payout for a given bet.
Create your Rainbet account and enter code SPINDEX during registration.
Get StartedEstimated typical sports margin by book - illustrative industry ranges, not Spindex-measured.
An implied probability calculator converts betting odds into a win percentage - the chance an outcome has according to the price. It's the single most useful number in betting, because it turns a confusing line into a plain probability you can compare against your own read of the game to decide whether a bet has value.
Implied probability is the win chance reflected in a set of odds, including the bookmaker's margin. When a book lists a team at -200, it's implying that team wins about 66.7% of the time. That figure isn't the true probability - it has the vig baked in - but it's the starting point for every value calculation in sports betting.
The formula depends on the odds format. For decimal odds, divide 1 by the decimal and multiply by 100 (2.00 = 50%). For positive American odds, it's 100 / (odds + 100), so +150 = 40%. For negative American odds, it's (-odds) / (-odds + 100), so -200 = 66.7%. For fractional odds a/b, it's b / (a + b), so 3/2 = 40%. This calculator runs all of these instantly and shows the result alongside your potential payout.
The point of implied probability is comparison. If a book implies a team has a 40% chance but you (or a sharp no-vig line) think the true chance is 45%, the odds are offering more than the outcome is worth - a positive expected value bet. Pairing this calculator with our no-vig calculator is the fastest way to spot those edges.
Enter a bet amount, then type into any odds field - fraction, decimal, American, or probability - and the rest convert instantly, along with your to-win and total payout. It's free, runs in your browser, and works for any sport or market.
Implied probability is the win chance baked into a set of odds - the bookmaker's estimate of how likely an outcome is, including their margin. For decimal odds it's 1 divided by the decimal price, so 2.00 equals a 50% implied probability.
For positive American odds, implied probability = 100 / (odds + 100). So +150 is 100 / 250 = 40%. For negative American odds, it's (-odds) / (-odds + 100). So -200 is 200 / 300 = 66.7%. This calculator handles both automatically.
Divide 1 by the decimal odds and multiply by 100. Decimal 2.00 is 1/2.00 = 50%; 1.50 is 1/1.50 = 66.7%; 4.00 is 25%. It's the simplest of the three formats.
For fractional odds written as a/b, implied probability = b / (a + b). So 3/2 is 2 / 5 = 40%, and 1/1 (evens) is 1 / 2 = 50%. Enter the fraction and the calculator converts it instantly.
Compare the odds-implied probability to your own (or the no-vig) estimate of the true chance. If you believe the real probability is higher than the implied probability, the bet has positive expected value (+EV) and is worth making.
Not on a real sportsbook line. Because of the vig, the implied probabilities of all outcomes total more than 100%. Removing that margin with a no-vig calculator gives you the fair probabilities, which do sum to 100%.
18+ only · Gamble responsibly · Tools are for informational purposes only.