Implied Probability Calculator
Implied probability is the chance a price corresponds to — before removing the sportsbook margin.
Implied probability includes the book's margin, so the two sides of a market add to more than 100%. Use the fair odds calculator to strip the margin out.
The formula
For positive American odds: implied probability = 100 / (odds + 100).
For negative American odds: implied probability = |odds| / (|odds| + 100).
Both forms work for any valid American price — this calculator applies the right one automatically based on the sign you enter.
Example
A price of +150 pays 1.5 times your stake. Its implied probability is 100 / (150 + 100) = 40%.
A price of -125 uses 125 / (125 + 100) = 55.56%. So you need to win more than 55.56% of those bets just to break even.
What the results mean
- Implied probability
- The chance the posted price corresponds to, margin included.
- Decimal and fractional odds
- The same price written in the formats used outside the US.
- Break-even win rate
- How often this bet must win for you to finish level over the long run.
Frequently asked questions
Keep reading
- What expected value means — how implied probability feeds EV
- Fair odds vs sportsbook odds — implied probability before and after de-vigging
- Vig Calculator — measure the margin in a two-way market
Analyzing a full parlay? Let EVScout check every leg automatically.
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