Odds converter
Enter odds in any format – decimal, fractional or American – and the other two are worked out along with the implied probability.
Implied probability: 40.0 %
How the converter works
In any of the three fields, enter odds in the format you know — decimal (e.g. 2.50), fractional (e.g. 3/2) or American, also called moneyline (e.g. +150 or −200). The other two formats and the implied probability are worked out instantly.
Decimal odds are the standard format used by bookmakers across Europe, fractional odds are used mainly in the UK and Ireland, and American odds are common in the US market. The implied probability shows the chance of the outcome the odds assume — calculated as 1 divided by the decimal odds, times 100.
How conversions between formats are calculated
From fractional to decimal, divide the numerator by the denominator and add 1 (e.g. 5/2 → 3.5). From positive American to decimal, divide the figure by 100 and add 1 (+150 → 2.5); from negative, divide 100 by the absolute value of the odds and add 1 (−200 → 1.5).
The other way round, decimal odds ≥ 2.0 give positive American odds as (odds − 1) × 100, and odds below 2.0 give negative odds as −100 / (odds − 1). The fractional form comes from reducing (odds − 1) to its simplest fraction.
Conversion examples
| Decimal | Fractional / American / probability |
|---|---|
| 2.50 | 3/2, +150, 40.0% |
| 1.50 | 1/2, −200, 66.7% |
| 3.00 | 2/1, +200, 33.3% |
Frequently asked questions
What is the difference between decimal, fractional and American odds?
All three express the same chance in a different notation. Decimal odds (2.50) are used across Europe, fractional odds (3/2) mainly in the UK and Ireland, and American odds (+150 or −200) in the US market.
How do I convert fractional odds to decimal?
Divide the numerator by the denominator and add 1. So 5/2 gives decimal odds of 3.5, and 1/2 gives 1.5.
What does the sign on American odds mean?
A positive figure (e.g. +150) shows how much you win on a stake of 100; a negative one (e.g. −200) shows how much you must stake to win 100. A value between −100 and +100 (other than zero) is invalid.
What is implied probability?
The chance of the outcome the odds suggest, calculated as 1 divided by the decimal odds, times 100. At odds of 2.50 that is 40%.
Why are some fractions rounded?
For odds that do not give an exact simple fraction, the calculator finds the nearest fraction with a sensible denominator — but for the vast majority of common odds an exact reduction comes out.
Does the decimal field accept a comma too?
Yes, you can enter odds with a comma or a full stop (e.g. 2,50 and 2.50) — internally they are always treated the same.