Implied Probability
The probability of an outcome as implied by the betting odds, including the bookmaker's margin.
Implied probability converts betting odds into a percentage chance of an outcome occurring. It reflects what the market believes the probability is, but it includes the bookmaker's margin (vig), so implied probabilities for all outcomes always sum to more than 100%.
Comparing implied probability to your own estimated probability is the foundation of value betting. If you believe a team has a 60% chance of winning but the odds imply only 50%, that's a +EV bet.
You can calculate implied probability from any odds format: American, decimal, or fractional.
Formula
For negative American odds: IP = |odds| / (|odds| + 100). For positive: IP = 100 / (odds + 100)Example
Odds of -150 imply a probability of 150 / (150 + 100) = 60%. Odds of +200 imply 100 / (200 + 100) = 33.3%.
Related Terms
Vig (Vigorish)
The commission a sportsbook charges on a bet, built into the odds.
True Odds
The actual mathematical probability of an outcome, without any bookmaker margin.
Expected Value (EV)
The average amount you can expect to win or lose per bet over time.
No-Vig Odds
The true fair odds after removing the sportsbook's built-in margin.
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