How the odds converter calculator works
Decimal, fractional and American odds all express the same price, and every price is also a probability. This converter shows all four at once from whichever format you enter.
- Decimal odds are the total return per unit staked, stake included.
- Fractional odds are profit to stake: decimal minus one, as a fraction.
- American odds show profit on 100 for prices over evens (positive) and the stake needed to win 100 for prices under evens (negative).
- Implied probability is 1 divided by the decimal odds.
Worked example
Enter 2.50.
- Fractional 6/4, American +150, implied probability 40%.
- Enter 1.50 and you get 1/2, −200 and 66.7%.
The implied probability includes the bookmaker's margin; across a whole market it adds up to more than 100%.
Questions
- Which format is easiest to reason with?
- Decimal, because return equals stake times price and probability is its simple inverse. The others are conventions of particular markets.
- Why does 2.00 equal +100 and 1/1?
- All three describe evens: a winning £1 stake returns £2, so the profit equals the stake.
- What about fractional odds like 11/10?
- Divide top by bottom and add one: 11/10 is 2.10 in decimal, which is +110 in American.
