Reviewed by CalcMulti Editorial Team·Last updated: ·← Probability Hub
Odds and probability both quantify likelihood, but they express it differently. Probability = successes / total outcomes. Odds = successes / failures. This converter handles all three major odds formats used worldwide.
Fractional odds (UK): 5/1 ("five-to-one") means you win 5 units for every 1 staked. Probability = 1 / (5+1) = 1/6 ≈ 16.67%. Decimal odds (Europe): 6.0 means your total return including stake is 6× your bet. Probability = 1/6.0 ≈ 16.67%. American odds (US): +500 means you win $500 on a $100 bet; −200 means you must bet $200 to win $100.
Implied probability is the probability embedded in a betting odds price. A bookmaker setting odds of 2.0 (1/1, "evens") implies they believe each outcome has a 50% chance. In practice, bookmakers add a "vig" (overround) so implied probabilities sum to >100%.
Worked example — American odds −150: P = 150 / (150 + 100) = 150/250 = 60%. American odds +200: P = 100 / (200 + 100) = 100/300 ≈ 33.33%.
p = 1 / decimal_odds | p = denominator / (numerator + denominator)
This calculator is for educational purposes only and does not constitute professional advice. Results are based on standard mathematical formulas. Always verify critical calculations with a qualified professional before making important decisions.