How to Calculate Implied Probability
- Enter your odds (American, Decimal, or Fractional format)
- Select the format from the dropdown
- Click Calculate Probability
- See the implied probability, true odds (without vig), and your edge
Implied Probability Formulas
From Decimal Odds
Implied % = (1 ÷ Decimal) × 100
Example: Decimal 2.50 → (1 ÷ 2.50) × 100 = 40%
From American Odds (Positive)
Implied % = 100 ÷ (American + 100) × 100
Example: +150 → 100 ÷ 250 × 100 = 40%
From American Odds (Negative)
Implied % = |American| ÷ (|American| + 100) × 100
Example: −200 → 200 ÷ 300 × 100 = 66.7%
From Fractional Odds
Implied % = Denominator ÷ (Numerator + Denominator) × 100
Example: 3/2 → 2 ÷ (3+2) × 100 = 40%
Understanding the Vig (Bookmaker Margin)
A typical football match market:
| Outcome | Offered Odds | Implied % |
|---|---|---|
| Home Win | 2.10 | 47.6% |
| Draw | 3.40 | 29.4% |
| Away Win | 3.20 | 31.3% |
| Total | — | 108.3% |
The 8.3% excess is the bookmaker’s margin — the “tax” on every bet.