Betting Odds Explained
Odds tell you two things: how likely an outcome is, and how much you would win. The same odds can be written three different ways — decimal, fractional and American (moneyline). This page explains each format and converts between them instantly.
The Three Odds Formats
- Decimal (2.50): the total you get back per $1 staked, including your stake. $10 at 2.50 returns $25. Common in Europe, Australia and Canada.
- Fractional (3/2): the profit relative to the stake. 3/2 means you win $3 for every $2 staked, plus your stake back. Common in the UK and Ireland.
- American / moneyline (+150): a positive number is the profit on a $100 stake; a negative number is how much you must stake to win $100. Common in the United States.
Implied Probability
Every set of odds contains an implied probability — the chance the outcome needs to have for the bet to be "fair". For decimal odds the formula is:
- Implied probability = (1 ÷ decimal odds) × 100
So odds of 2.50 imply a (1 ÷ 2.50) × 100 = 40% chance. Comparing the implied probability to your own estimate is how bettors judge whether odds offer value.
Conversion formulas
- Decimal → Implied % = (1 / decimal) × 100
- Decimal → Fractional = decimal − 1 (as a fraction)
- Decimal → American = (decimal − 1) × 100 if decimal ≥ 2, else −100 / (decimal − 1)
Frequently Asked Questions
What do betting odds mean?+
Odds show how likely an outcome is and how much you would win. Higher odds mean a less likely outcome and a bigger potential payout.
How do I convert decimal odds to fractional?+
Subtract 1 from the decimal odds and express the result as a fraction. For example, 2.50 − 1 = 1.50 = 3/2.
What is implied probability?+
Implied probability is the chance an outcome needs to have for the odds to be fair. For decimal odds it is (1 / odds) × 100. Odds of 2.00 imply a 50% chance.
What is the difference between decimal and American odds?+
Decimal odds show total return per $1 including stake. American odds show profit on $100 (positive) or the stake needed to win $100 (negative). They describe the same thing differently.
Are these odds tools free?+
Yes. This is a free educational tool to help you understand and convert betting odds — no account needed.