Implied probability expresses an odds quote as a break-even percentage. It is useful for comparison, but a bookmaker quote usually includes margin.
Last reviewed: 2026-08-10
Decimal odds
Divide one by decimal odds. Decimal odds of 2.50 imply 40%, while 1.67 implies about 59.9%.
American odds
For positive odds, divide 100 by the odds plus 100. For negative odds, divide the absolute value by that value plus 100.
Fractional odds
For a fraction A/B, divide B by A plus B. Fractional odds of 3/2 imply 2 divided by 5, or 40%.
Implied is not the same as fair
A complete market can add to more than 100% because of margin. Use a no-vig calculation before treating a market quote as a fair probability estimate.
Step-by-step workflow
- 1Identify the odds format.
- 2Apply the matching conversion formula.
- 3Express the result as a percentage.
- 4Check market margin before interpreting it as fair probability.
Frequently asked questions
Can implied probability exceed 100%?
A valid individual outcome should not, but the probabilities across a priced market commonly sum above 100% because of margin.
What does +200 imply?
Positive American odds of +200 imply approximately 33.33%.