Odds Converter
Type odds in any one format, decimal, fractional, American or a probability, and the converter shows all four, together with the profit and total return for your stake. A second box takes one set of odds per line for all the outcomes of an event and works out the bookmaker margin, also called the overround, and the fair chance of each outcome once the margin is removed. Everything runs in your browser.
| Outcome | Decimal | Implied | Fair chance | Fair decimal |
|---|---|---|---|---|
| 1 | 2.1 | 47.62% | 45.43% | 2.20 |
| 2 | 3.4 | 29.41% | 28.06% | 3.56 |
| 3 | 3.6 | 27.78% | 26.50% | 3.77 |
Decimal odds are the total return for each 1 staked, stake included. Fractional odds are profit over stake, so 3/2 pays 3 for every 2 staked. American odds show the profit on a 100 stake when positive and the stake needed to win 100 when negative. The implied probability is 1 divided by the decimal odds. It includes the bookmaker margin, which the fair chance column removes by scaling all outcomes in proportion. That is a common approximation, not the only method. This tool is for working out numbers and is not betting advice. Everything runs in your browser.
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Math & MoneyAbout the Odds Converter
The same price can be written four ways. Decimal odds of 2.50 return 2.50 for each 1 staked, stake included. The same price as fractional odds is 3/2, which means 3 of profit for every 2 staked. As American odds it is +150, a 150 profit on a 100 stake, and as an implied probability it is 40%, which is 1 divided by 2.50. Negative American odds work the other way: -110 means staking 110 to win 100, which is 1.909 in decimal and an implied probability of 52.38%. The converter does all of this through decimal odds. To check a margin, add up the implied probabilities of every outcome. Decimal odds of 2.10, 3.40 and 3.60 imply 47.62%, 29.41% and 27.78%, which total 104.81%, so the bookmaker margin is 4.81%. Dividing each implied probability by the total gives the fair chances of 45.43%, 28.06% and 26.50%. That proportional method is a common approximation and not the only way to remove a margin. The tool does the arithmetic only and is not betting advice.
How do I convert fractional odds to decimal?▾
Divide the top number by the bottom number and add 1. The odds 3/2 become 3 / 2 + 1 = 2.50.
What do positive and negative American odds mean?▾
Positive odds such as +150 are the profit on a 100 stake. Negative odds such as -200 are the stake needed to win 100.
How do I get the implied probability from decimal odds?▾
Divide 1 by the decimal odds. Odds of 2.50 imply 1 / 2.50 = 40%.
What is the overround?▾
It is the amount by which the implied probabilities of all outcomes add up to more than 100%. It is the bookmaker margin built into the prices.
Is my data uploaded?▾
No. The calculation runs in your browser and nothing you enter is sent anywhere.