Odds converter: compare the price, not just the format
The same odds can look very different as a decimal, a fraction or an American moneyline. This converter puts those formats beside each other and shows the implied probability behind the price. It does not find live odds or judge whether a bet offers good value.
Decimal and fractional odds explained
Decimal odds describe the total return per unit staked if the bet wins. At 2.50, a 100-unit stake returns 250 units. That includes the original 100, leaving 150 units of profit.
Fractional odds describe profit relative to the stake. The fraction 3/2 means 3 units of profit for every 2 staked. Divide 3 by 2, then add 1 for the stake: 3/2 + 1 = 2.50 in decimal odds.
Positive and negative American odds
Positive American odds show profit on a 100-unit stake. For +150, divide 150 by 100 and add 1: the decimal price is 2.50. The equivalent fraction is 3/2 and the implied probability is 40%.
Negative American odds show the stake needed to make 100 units of profit. At −200, 200 units are needed to make 100. The decimal price is 1 + 100/200 = 1.50, equivalent to 1/2 and about 66.67% implied probability. Both +100 and −100 represent even odds; this converter displays +100.
Implied probability and bookmaker margin
To convert decimal odds into a percentage, divide 100 by the odds. At 2.50, the calculation is 100/2.50 = 40%. Working in the other direction, a 25% probability corresponds to decimal odds of 100/25 = 4.00.
That percentage is implied by the price, not a measured chance of winning. For two mutually exclusive outcomes that cover every result, prices of 1.91 and 1.91 imply about 52.36% each, or 104.71% in total. The amount above 100% is the market overround. This single-price converter does not remove it or calculate a fair probability.
Read profit separately from total return
Enter an optional stake to see what a winning bet would return. Total return is stake × decimal odds. Net profit is that total minus the stake. For 20 units at 4.00, the total return is 80 and the profit is 60.
The calculation assumes a normal win at the entered price, with no commission, tax, bonus conditions or partial settlement. A losing bet loses its stake. Returns are rounded to 0.01 unit; a bookmaker or exchange may settle differently.
Precision and supported inputs
The tool supports prices equivalent to decimal odds from 1.000001 to 10,000. Fractional inputs use positive whole numbers separated by a slash. A dot or comma can be used as the decimal separator in other inputs; do not include thousands separators.
Decimal displays use up to six places; American odds and percentages use up to four. Fractions use a denominator of at most one million. Values marked ≈ are rounded. Switching formats retains the original price and its calculated return, even when a displayed fraction is approximate. Editing the input establishes a new price.
Odds conversion table, including a price in cents
A prediction-market contract quoted in cents can be read as an implied probability. A 62¢ contract implies p = 0.62. The same value converts to decimal, American and fractional odds with the ordinary formulas. Kalshi and Polymarket are examples of markets that display prices in cents; this page does not recommend either venue.
- Decimal odds = 1 / p. For p = 0.62, 1 / 0.62 ≈ 1.6129.
- American odds, when p is greater than 0.5: −100 × p / (1 − p). For p = 0.62, −100 × 0.62 / 0.38 ≈ −163.
- Fractional odds = (1 − p) / p. For p = 0.62, 0.38 / 0.62 = 19/31.
| Input | Implied probability | Decimal | American | Fractional |
|---|---|---|---|---|
| 62¢ | 62% | 1.6129 | −163 | 19/31 |
| Decimal 2.00 | 50% | 2.00 | +100 | 1/1 |
| American −110 | 52.38% | 1.9091 | −110 | 10/11 |
American −110: implied probability = 110 / (110 + 100) = 0.52381…, or 52.38%. Decimal = 1 / 0.52381… ≈ 1.9091. These are raw implied probabilities from a single price. They are not de-vigged, and they are not a forecast.
Vig, or overround, is the amount by which the implied probabilities in a full market exceed 100%. A single converted price already includes that margin. If you are combining several legs, the Parlay Calculator shows how the combined price is formed.