Implied probability calculator
Implied probability is the chance of an outcome that a price represents: 1 ÷ decimal odds. Odds of 2.50 imply a 40% chance — including the bookmaker margin.
Updated 19 October 2026 · Free, no sign-up. All calculations run in your browser. 18+ · Play responsibly.
How it works
Enter odds in any format. The calculator shows the implied probability and the same price in the other two formats.
The formula
Implied probability = 1 ÷ decimal odds
American +X → 1 + X/100 · American −X → 1 + 100/X · Fractional a/b → 1 + a/b
Worked example
Odds of 2.50 = +150 = 3/2, and 1 ÷ 2.50 = 40%. If you believe the real chance is higher than 40%, the price has value.
Why the probabilities add up to more than 100%
Add up the implied probabilities of all outcomes in a market and you get more than 100%. The excess is the bookmaker margin. Remove it with the no-vig calculator to get fair probabilities.
FAQ
Is implied probability the real chance?
No — it includes the bookmaker margin, so it is slightly higher than the real chance. Remove the margin to estimate the fair probability.