Table of Contents
What Is Implied Probability?
Implied probability is the conversion of betting odds into a percentage that reflects the likelihood of an event occurring according to the bookmaker. It includes the bookmaker's margin (vig), so the total implied probabilities for all outcomes typically exceed 100%.
Understanding implied probability helps bettors identify value bets where their assessed probability differs from what the odds suggest. It is a fundamental concept in sports betting, financial markets, and risk assessment.
Conversion Formulas
Reference Table
| American | Decimal | Fractional | Implied Prob |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.67% |
| -110 | 1.91 | 10/11 | 52.38% |
| +100 | 2.00 | 1/1 | 50.00% |
| +150 | 2.50 | 3/2 | 40.00% |
| +300 | 4.00 | 3/1 | 25.00% |
Frequently Asked Questions
Why do implied probabilities add up to more than 100%?
Bookmakers include a margin (vigorish or juice) in their odds. This ensures they make a profit regardless of the outcome. The excess over 100% represents the bookmaker's edge.
How do I find a value bet?
A value bet exists when you believe the true probability of an event is higher than the implied probability from the odds. If you think a team has a 60% chance of winning but the odds imply only 50%, that represents positive expected value.
What is the difference between odds formats?
American odds use +/- notation common in the US. Decimal odds (popular in Europe) show total return per unit staked. Fractional odds (popular in UK) show profit relative to stake. All express the same underlying probability.