Odds converter
Type odds in any format: fractional (5/2), decimal (3.5) or American (+250 or -200).
Written by BettingSeeker Editorial Team
How odds formats work
Fractional odds are traditional in the UK and Ireland. 5/2 means you win 5 for every 2 staked, plus your stake back.
Decimal odds are used across Europe, Australia and Canada, and by most betting exchanges. The number is the total return per 1 unit staked, stake included, so 3.50 returns 35 from a 10 stake.
American odds are used in the US. A plus sign shows the profit on a 100 stake (+250 wins 250). A minus sign shows how much you must stake to win 100 (-200 means stake 200 to win 100).
Worked examples
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/2 | 1.50 | -200 | 66.7% |
| 1/1 (evens) | 2.00 | +100 | 50.0% |
| 5/2 | 3.50 | +250 | 28.6% |
| 10/1 | 11.00 | +1000 | 9.1% |
The formulas
- Fractional to decimal: (numerator ÷ denominator) + 1
- Decimal to American: if decimal ≥ 2, (decimal − 1) × 100; otherwise −100 ÷ (decimal − 1)
- Implied probability: 1 ÷ decimal odds
Frequently asked questions
What is the difference between fractional, decimal and American odds?
They are three ways of writing the same price. Fractional odds (5/2) show profit relative to stake, decimal odds (3.50) show the total return per 1 unit staked, and American odds (+250 or -200) show the profit on a 100 stake or the stake needed to win 100.
What does implied probability mean?
It is the chance of the outcome that the odds suggest, ignoring the bookmaker margin. For decimal odds it is 1 divided by the odds, so 2.00 implies 50%.
Why does my converted fraction look unusual?
Bookmakers round to familiar fractions. The converter shows the nearest simple fraction with a denominator up to 100, so a decimal price like 2.37 appears as 137/100 rather than a rounded bookmaker fraction such as 11/8.