Win Probability Calculator
Professional-grade odds converter and risk analyzer. Calculate implied probabilities, remove bookmaker vig (margin), build parlays, and simulate payouts for American, Decimal, and Fractional formats.
About
In the domain of probabilistic finance and sports analytics, the Win Probability Calculator serves as a critical bridge between abstract market notations and actionable risk assessment. Betting markets express probabilities through various Odds Formats - American, Decimal, and Fractional - each obscuring the raw statistical likelihood of an event. This tool decodes these formats into a singular truth: Pimplied (Implied Probability).
However, raw implied probability is often misleading due to the Bookmaker's Overround (or "Vig"). Markets are priced such that the sum of probabilities exceeds 100%, guaranteeing a theoretical profit for the house. Professional analysis requires stripping this margin to reveal the True Probability. This application provides granular control over these variables, allowing users to convert odds, calculate margins, and construct multi-event compound probabilities (Parlays) with arithmetic precision.
Formulas
1. Conversion to Implied Probability (P):
2. True Probability (Vig Removal):
First, calculate the Market Overround (Ω) by summing the implied probabilities of all outcomes:
Ω = n∑i=1 Pi
Then normalize each outcome to find the True Probability (Ptrue):
Ptrue = PimpliedΩ
Reference Data
| Implied Probability | Decimal (EU) | American (US) | Fractional (UK) | Risk Profile |
|---|---|---|---|---|
| 95.24% | 1.05 | -2000 | 1/20 | Certainty |
| 90.91% | 1.10 | -1000 | 1/10 | Very Low |
| 80.00% | 1.25 | -400 | 1/4 | Low |
| 75.00% | 1.33 | -300 | 1/3 | Low |
| 66.67% | 1.50 | -200 | 1/2 | Moderate |
| 60.00% | 1.67 | -150 | 4/6 | Moderate |
| 54.55% | 1.83 | -120 | 5/6 | Standard Flip |
| 52.38% | 1.91 | -110 | 10/11 | Standard Vig |
| 50.00% | 2.00 | +100 | 1/1 | Coin Toss |
| 40.00% | 2.50 | +150 | 3/2 | High |
| 33.33% | 3.00 | +200 | 2/1 | High |
| 25.00% | 4.00 | +300 | 3/1 | Very High |
| 20.00% | 5.00 | +400 | 4/1 | Longshot |
| 10.00% | 10.00 | +900 | 9/1 | Extreme |
| 1.00% | 100.00 | +9900 | 99/1 | Lottery |