How to Calculate Odds: Complete Guide
Master the art of odds calculation with this comprehensive step-by-step guide covering all major betting formats.
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Before learning how to calculate odds, it's essential to understand the three main formats used in sports betting: decimal odds, fractional odds, and moneyline (American) odds. Each format represents the same probability but displays it differently.
1. How to Calculate Decimal Odds
Decimal odds are the most straightforward format for calculations. They represent the total amount you'll receive for every $1 wagered, including your original stake.
Decimal Odds Formula:
Total Return = Bet Amount × Decimal Odds
Profit = (Bet Amount × Decimal Odds) - Bet Amount
Example:
If you bet $100 on odds of 2.50:
• Total Return = $100 × 2.50 = $250
• Profit = $250 - $100 = $150
2. How to Calculate Fractional Odds
Fractional odds show the ratio of profit to stake. They're popular in the UK and Ireland.
Fractional Odds Formula:
Profit = Bet Amount × (Numerator ÷ Denominator)
Total Return = Bet Amount + Profit
Example:
If you bet $100 on odds of 3/2:
• Profit = $100 × (3 ÷ 2) = $100 × 1.5 = $150
• Total Return = $100 + $150 = $250
3. How to Calculate Moneyline Odds
Moneyline odds use positive and negative numbers. Positive odds show profit on a $100 bet, while negative odds show how much you need to bet to win $100.
Moneyline Odds Formulas:
Positive odds (+): Profit = Bet Amount × (Odds ÷ 100)
Negative odds (-): Profit = Bet Amount × (100 ÷ |Odds|)
Examples:
+150 odds: $100 bet → Profit = $100 × (150 ÷ 100) = $150
-200 odds: $100 bet → Profit = $100 × (100 ÷ 200) = $50
Converting Between Odds Formats
Decimal to Fractional
Fractional = (Decimal - 1) ÷ 1, then simplify
Decimal to Moneyline
If Decimal ≥ 2.00: Moneyline = (Decimal - 1) × 100
If Decimal < 2.00: Moneyline = -100 ÷ (Decimal - 1)
Calculating Implied Probability
Implied probability shows the likelihood of an outcome according to the odds. This is crucial for identifying value bets.
Implied Probability Formula:
Implied Probability = 1 ÷ Decimal Odds × 100%
Example:
Odds of 2.50 → Implied Probability = 1 ÷ 2.50 × 100% = 40%
Practical Tips for Odds Calculation
- Use decimal odds for quick calculations - they're the most straightforward format
- Always calculate implied probability - compare it with your own assessment to find value
- Round appropriately - most sportsbooks round to 2 decimal places
- Practice with small amounts - master the calculations before betting larger sums
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