No-Vig Fair Odds Calculator
Strip bookmaker margin (overround) to extract true implied probability across Multiplicative, Additive, Power, and Shin models.
Overround
The bookmaker's theoretical profit margin. Positive means they have an edge.
Result
| Calculation Method | Out 1 | Out 2 |
|---|---|---|
| Multiplicative P_fair_i = (1/O_i) / Σ(1/O_k) | - | - |
| De-vigged Odds | - | - |
| Additive P_fair_i = (1/O_i) - margin/n | - | - |
| De-vigged Odds | - | - |
| Power P_fair_i = (1/O_i)^k where Σ(1/O_i)^k = 1 | - | - |
| De-vigged Odds | - | - |
| Shin Find z where Σ(sqrt(z² + 4(1-z)(1/O_i)²) - z)/(2(1-z)) = 1 | - | - |
| De-vigged Odds | - | - |
FAQ
What is 'vig' or 'juice'?
Vig (vigorish) or juice is the built-in profit margin bookmakers add to their odds, ensuring they make money over time regardless of the outcome.
Why do I need to calculate 'fair' odds?
Removing the vig helps you find the true probability of an outcome as estimated by the market, which is crucial for identifying +EV (Expected Value) bets.
What is overround?
Overround is the percentage by which the sum of the implied probabilities of all possible outcomes exceeds 100%. This excess represents the bookmaker's margin.
Which de-vigging method is best?
The Shin method is often considered the most accurate as it accounts for insider trading and uneven distribution of public money, but Multiplicative is easiest and widely used.
Can I use this for 3-way markets like soccer?
Yes, this calculator supports both 2-way (e.g., basketball spreads) and 3-way (e.g., soccer match winner) markets.