Sports Betting Implied Probability & Vig Convert American odds to implied probability and calculate the book's overround. Team 1 Odds (e.g., -110) Team 2 Odds (e.g., -110) Calculate Vig Team 1 Implied Prob: Team 2 Implied Prob: Total Overround (Vig): Formula: Negative Odds: Odds / (Odds - 100). Positive Odds: 100 / (Odds + 100).