How to Read Betting Odds: Decimal, Fractional & American

Understanding Betting Odds Formats

Betting odds are displayed in three main formats worldwide. Understanding all three helps you compare odds across international bookmakers.

Decimal Odds (European)

Decimal odds are the most straightforward format, popular in Europe, Australia, and on betting exchanges.

How They Work

Odds represent total return (stake + profit)

Multiply stake by odds to get total return

Example

Odds: 2.50, Stake: $100

Total Return: $100 × 2.50 = $250

Profit: $250 - $100 = $150

Converting to Probability

Implied Probability = 1 / Decimal Odds × 100

Odds 2.50 = 1/2.50 = 40% implied probability

Fractional Odds (UK)

Traditional format used mainly in the UK and Ireland.

How They Work

Show profit relative to stake

5/2 means "5 to 2" - win $5 for every $2 staked

Example

Odds: 5/2, Stake: $100

Profit: $100 × (5/2) = $250

Total Return: $250 + $100 = $350

Common Fractional Odds

| Fractional | Decimal | Probability ||------------|---------|-------------|| 1/1 (evens) | 2.00 | 50% || 1/2 | 1.50 | 66.7% || 2/1 | 3.00 | 33.3% || 5/1 | 6.00 | 16.7% || 10/1 | 11.00 | 9.1% |

American Odds (Moneyline)

Used primarily in the United States. Shows how much you need to bet or how much you win on $100.

Positive Odds (+150)

Shows profit on $100 stake

+150 means bet $100 to win $150

Negative Odds (-150)

Shows how much to bet to win $100

-150 means bet $150 to win $100

Example

| American | Decimal | Stake $100 | Profit ||----------|---------|------------|--------|| +200 | 3.00 | $100 | $200 || -200 | 1.50 | $100 | $50 || +150 | 2.50 | $100 | $150 || -150 | 1.67 | $100 | $67 |

Conversion Formulas

Decimal to Fractional

(Decimal - 1) as fraction

2.50 → 1.50 → 3/2

Decimal to American

If decimal ≥ 2.00: (Decimal - 1) × 100 = +American

If decimal < 2.00: -100 / (Decimal - 1) = -American

American to Decimal

Positive: (American / 100) + 1

Negative: (100 / |American|) + 1

Why Odds Formats Matter

Finding Value

Different bookmakers use different formats. To compare odds effectively:

1. Convert everything to decimal

2. Calculate implied probability

3. Compare with your estimated probability

Using Scorecast

Scorecast displays all odds in decimal format by default, making comparison easy across 20+ bookmakers.

The Overround (Bookmaker Margin)

Bookmakers build in a margin by offering odds slightly below true probability.

Example: Coin Flip

True odds: 2.00 for heads, 2.00 for tails

Bookmaker odds: 1.91 for heads, 1.91 for tails

Overround: (1/1.91 + 1/1.91) - 1 = 4.7% margin

Finding the Best Odds

Always compare odds before betting. A difference of 2.00 vs 2.10 might seem small, but over 1,000 bets it's a 5% difference in returns!

Use Scorecast's odds comparison to instantly find the best price across all major bookmakers.