Don't care? Head to our probability calculator
Don't care? Head to our probability calculator
It can be helpful to quickly calculate the implied probability of an odd. I want to use a real example, so I found the odd for Spain to win the FIFA World Cup in 2026 in three different formats on three different sportsbooks: +600, 7.000, and 11/2. Let's convert these odds into percentages using each odd's formula.
American odds have two different formulas: one for positive odds and one for negative odds.
Example: Spain to win 2026 FIFA World Cup at +600 odds.
Step 1. +600 is a positive odd so we use the first equation.
Step 2. Fill in the variable and solve for the implied probability.
Implied Probability(%) = (100/(600+100))*100% = (100/700)*100% ≈ 14.2857%
Example: Spain to win 2026 FIFA World Cup at 7.000 odds.
Implied Probability(%) = (1/7.00)*100% ≈ 14.2857%
Example: Spain to win 2026 FIFA World Cup at 11/2 odds.
Implied Probability(%) = (2/(11+2))*100% = (2/13)*100% ≈ 15.385%
This isn't the easiest math to do on the fly so it's worth memorizing some key odds and getting a sense for these different formats.
For American odds you need to remember that there are two ranges of odds:
-∞ ≤ odds ≤ -100
AND
+100 ≤ odds ≤ ∞
The first range represents teams that are 50% or more likely to win. Smaller numbers represent heavier favorites1 i.e. a team at -4000 is a heavier favorite than a team at -120.
The second range represents teams that are 50% or less likely to win. Larger numbers represent bigger underdogs i.e. a team at +4000 is a bigger underdog than a team at +120.
The graph below shows the relationship between American odds and implied probability.
There is only one continuous range of decimal odds:
1 ≤ odds
50% probability is represented by a decimal odd of 2.00, so an odd between 1.00 and 2.00 represents an outcome that the book believes is more than 50% likely to occur, and an odd over 2.00 represents an outcome that the book believes is less than 50% likely to occur. Remember that this is not a linear function.
The graph below shows the relationship between decimal odds and implied probability.
Fractional Odds are very similar to decimal odds; there is one continuous range of odds:
0 ≤ odds
50% probability is represented by 1/1 so any fractional odd that equals a number that is less than one (i.e. the denominator is larger than the numerator) represents an outcome that the book believes has a probability greater than 50%. Conversely, any fraction that equals a number that is greater than one (i.e. the numerator is larger than the denominator) represents an outcome that the book believes has a probability less than 50%.
The graph below shows the relationship between fractional odds and implied probability.
You don't have to memorize these equations and it can be difficult to develop an instinct for a non-linear relationship between numbers, but developing your familiarity with the implied probability of your preferred odds format will only help you out. And when you're in a pinch you can always use our odds calculator or our odds converter.
Next up: Hedging Your Bet
1While most teams with odds that imply a winning probability over 50% are favorites, this is not always the case. Please consider every pair/set of odds separately. (Not sure how this is possible? Learn about vig.)
