Odds Converter (Decimal, American, Fractional & More)
Type odds in any format and see them in all the others at once: decimal, American (moneyline), fractional, implied probability, and prediction-market cents (¢, the Polymarket-style price).
Fill in the fields above to see the result.
The six formats on this page describe exactly the same thing. The difference is geographic and historical, not mathematical. The converter above exists because comparing prices across books that speak different formats, by eye, is like comparing prices in different currencies without knowing the rate.
How the math works
Everything routes through decimal, which is the central format because it already is the multiplier on your return.
American (moneyline). A positive line is what you profit staking 100; a negative one is what you must stake to profit 100.
decimal ≥ 2.00 → american = (decimal − 1) × 100 decimal < 2.00 → american = −100 ÷ (decimal − 1)
Fractional. It is net profit as a fraction of the stake. The converter approximates with the best fraction up to a denominator of 100, which is the British bookmaking convention.
fractional = decimal − 1, written as a fraction
Hong Kong. Net profit per unit, in decimal. Literally decimal − 1.
Probability and cents. The same number in different clothes: 100 ÷ decimal. The cents format comes from prediction markets, where a contract paying 1 costs as many cents as the probability.
Worked example
| Decimal | American | Fractional | Hong Kong | Probability | Cents |
|---|---|---|---|---|---|
| 1.50 | −200 | 1/2 | 0.50 | 66.7% | 66.7¢ |
| 2.00 | +100 | 1/1 | 1.00 | 50.0% | 50.0¢ |
| 2.10 | +110 | 11/10 | 1.10 | 47.6% | 47.6¢ |
| 4.00 | +300 | 3/1 | 3.00 | 25.0% | 25.0¢ |
The 2.00 row is the hinge of the American format: it is where the sign flips. Above 2.00 lines are positive, below they are negative, and that is why −110 and +110 are not symmetric despite looking it. The first implies 52.4% and the second 47.6%.
Where it misleads
Fractional is approximate. 11/10 is exact for 2.10, but many decimals have no clean fraction with a small denominator. The converter picks the best approximation up to 100, which is what bookmakers do, so the rounding matches what you see on their screens.
Odds alone are not value. Converting does not judge. A pretty price in any format is still a bad one if the true probability is worse than the implied.
Cents is not a traditional bet. In a prediction market you buy a contract that can be sold before the end, and liquidity behaves differently. The number converts; the product is not the same.
FAQ
Which format is best for calculating?
Decimal, with no competition. Total return is stake × odds, and comparing two prices is comparing two numbers pointing the same way. The other formats exist out of regional habit.
Why does −110 show up so often?
Because it is the standard price on both sides of a balanced market in the United States. Each side implies 52.4%, the two add up to 104.8%, and that 4.8% is the bookmaker's commission.
What do fractional odds of 11/10 mean?
That you profit 11 for every 10 staked, on top of getting your stake back. In decimal that is 1 + 11/10 = 2.10.
To read any format as probability, the implied probability calculator isolates that step. The odds formats guide explains where each one came from. Betting is entertainment for adults 18 and over and carries a risk of loss.