Odds converter: decimal, fractional and American
Type a price in the format your bookmaker shows. The converter gives the two other formats and the chance the price stands for.
Common odds in all three formats
| Decimal | Fractional | American | Implied probability |
|---|---|---|---|
| 1.20 | 1/5 | −500 | 83.33% |
| 1.50 | 1/2 | −200 | 66.67% |
| 1.80 | 4/5 | −125 | 55.56% |
| 1.91 | 91/100 | −110 | 52.36% |
| 2.00 | 1/1 | +100 | 50.00% |
| 2.50 | 3/2 | +150 | 40.00% |
| 3.00 | 2/1 | +200 | 33.33% |
| 5.00 | 4/1 | +400 | 20.00% |
| 10.00 | 9/1 | +900 | 10.00% |
How one price turns into the others
All three formats say the same thing: how much a winning bet returns. Decimal odds are the total return per unit staked. Fractional odds leave the stake out and show profit over stake. American odds show the profit on a stake of 100 when positive, and the stake needed to win 100 when negative. The implied probability is one divided by the decimal price.
Worked example
A price of 2.50 is 3/2 as a fraction and +150 in American form. Staking 100 returns 250, of which 150 is profit. The price implies a chance of 40.00%.
To see how much of that probability is margin, put both sides of the market into the bookmaker margin calculator. Once you have your own estimate of the chance, the Kelly stake calculator sizes the bet, and the arbitrage calculator compares prices across bookmakers.
What a converted price does not tell you
- An implied probability is the view of the bookmaker with the margin added. It is not the true chance of the result.
- Fractions are rounded to the nearest simple one, so 1.91 shows as a fraction that is very close, not always exact.
- A format changes how a price looks. It never changes what the bet pays.
Questions about odds formats
What do American odds of −200 mean?
You stake 200 to win 100. In decimal form that is 1.50, as a fraction 1/2, and it implies a chance of 66.67%.
Which decimal price is even money?
A price of 2.00, written +100 in American form. It implies 50.00%, and a bet at that price needs to win half the time to break even.
Why do the two sides of a market add up to more than 100%?
Because of the margin. Two sides priced at 1.91 imply 52.36% each, 104.71% together. The part above 100% is what the bookmaker keeps on average.
Is a decimal price the same as a casino multiplier?
Yes in form: both are the total return per unit staked. The difference is that a casino game has a known chance behind the multiplier, while a sports price is an estimate.