Implied probability calculator
Every price says how likely the book thinks something is, plus its margin. Type odds in any format to see the implied chance; the no-vig calculator takes the book's cut out.
The formula
implied chance = 1 / decimal odds
For American odds: positive odds A give 100 / (A + 100); negative odds −A give A / (A + 100). So -110 is 110 / 210 = 52.38%, and +150 is 100 / 250 = 40.00%.
Why the chances add up to more than 100%
Both sides of a -110 / -110 game imply 52.38%, together 104.76%. The extra 4.76 points is the book's margin, which the vig calculator turns into a hold of 4.55%. To get the chance with the margin taken out, use the no-vig calculator.
Using implied probability
If you think a team wins more often than its odds imply, the price is +EV for you. The hard part is being right.
Questions
How do you calculate implied probability from odds?
Divide 1 by the decimal odds. For American odds, positive A gives 100 / (A + 100); negative -A gives A / (A + 100).
What is the implied probability of -110?
52.38%: 110 / (110 + 100).
Why do implied probabilities add up to more than 100%?
Because the sportsbook's margin (vig) is built into the odds. The amount over 100% is that margin.
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Updated 2026-10-26