Implied Probability
The win probability suggested by a betting line. The math foundation for finding +EV bets.
Implied probability converts an odds line into a percentage chance of winning. It’s the foundation of every value calculation.
Conversion formulas (American odds):
- Negative line:
odds ÷ (odds + 100); Example: -200 → 200/300 = 66.7% - Positive line:
100 ÷ (odds + 100); Example: +150 → 100/250 = 40%
Combined implied probability across both sides of a market exceeds 100% because of the vig. That overround is the book’s structural edge.
If your estimated true probability beats the implied number, you have a +EV bet.