All three formats describe the same relationship between stake, profit and total return. Decimal odds include the returned stake. Fractional odds describe potential profit relative to stake. American odds use either the profit on a 100-unit stake or the stake needed to win 100 units.
Converting odds into implied probability
Divide 100 by the decimal price. Decimal odds of 3.50 imply 28.57% before accounting for bookmaker margin. This is a market-implied figure, not an objective forecast.
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/2 | 1.50 | -200 | 66.67% |
| Evens | 2.00 | +100 | 50.00% |
| 5/2 | 3.50 | +250 | 28.57% |
| 9/1 | 10.00 | +900 | 10.00% |
Conversions may be rounded to familiar fractional prices. Always compare the original decimal number when small pricing differences matter.