SPORTS BETTING MATH
No-Vig Fair Odds Calculator

No-Vig Fair Odds Calculator

Compare Multiplicative, Additive, Power and Shin probability estimates under their stated margin-allocation assumptions.

Overround

0.00%

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)

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De-vigged Odds - -
Additive
P_fair_i = (1/O_i) - margin/n

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De-vigged Odds - -
Power
P_fair_i = (1/O_i)^k where Σ(1/O_i)^k = 1

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De-vigged Odds - -
Shin
Find z where Σ(sqrt(z² + 4(1-z)(1/O_i)²/S) - z)/(2(1-z)) = 1; S = Σ(1/O_k)

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De-vigged Odds - -
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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?

Each method estimates probabilities under different assumptions. Shin models insider trading; no method is universally most accurate.

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.