Implied probability translates betting odds into percentage form.
This percentage represents how likely the market believes an outcome is.
Without calculating implied probability, you cannot evaluate value.
Decimal Odds Formula
For decimal odds:
Implied Probability (%) = 1 ÷ Odds × 100
Example:
Odds 2.00
1 ÷ 2.00 = 0.50 → 50%
Odds 1.80
1 ÷ 1.80 ≈ 0.5556 → 55.56%
Odds 3.00
1 ÷ 3.00 ≈ 0.3333 → 33.33%
This is the break-even percentage required to make the bet profitable long-term.
American Odds Formula
For positive American odds (+150):
Implied Probability = 100 ÷ (Odds + 100) × 100
Example:
+150
100 ÷ (150 + 100) = 100 ÷ 250 = 40%
For negative American odds (-200):
Implied Probability = |Odds| ÷ (|Odds| + 100) × 100
Example:
-200
200 ÷ (200 + 100) = 66.67%
Fractional Odds Formula
For fractional odds (3/2):
Implied Probability = Denominator ÷ (Numerator + Denominator) × 100
Example:
3/2
2 ÷ (3 + 2) = 40%
What Implied Probability Means
If implied probability is 40%:
The outcome must happen at least 40% of the time to break even.
If your estimated probability is higher → positive expected value.
If lower → negative expected value.
Multi-Outcome Markets
In markets like 1X2:
Add all implied probabilities together.
If the total exceeds 100%, the excess is bookmaker margin.
Example:
Home 45%
Draw 30%
Away 28%
Total = 103%
Margin = 3%
Why This Is Essential
Every betting decision should start with:
What probability does the market assign?
What probability do I assign?
No probability comparison means no value assessment.
Core Principles
Implied probability converts odds into percentages.
Decimal formula: 1 ÷ Odds × 100.
American and fractional formats have equivalent formulas.
Compare implied probability with your estimate.
Value begins with accurate calculation.
