This one-page chart converts fractional, decimal and American odds, and shows the chance each price implies. Find a price in any column and read across to the other formats. Fractional 5/2, decimal 3.50 and American +250 are the same price, so all three imply a 28.6% chance.
Print it on one page and keep it beside you when you read a price. If your printer uses A4 paper, choose “Fit to page”. For a price that is not on the chart, use the odds converter.
What does the odds conversion chart show?
The chart lists 46 common prices, from 1/10 to 100/1. Each row gives the fractional, decimal and American form and the implied probability, which is the chance the price needs to be right just to break even. Short prices sit at the top, long prices at the bottom.
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/4 | 1.25 | -400 | 80.0% |
| 1/2 | 1.50 | -200 | 66.7% |
| 10/11 | 1.91 | -110 | 52.4% |
| 1/1 (even money) | 2.00 | +100 | 50.0% |
| 6/4 | 2.50 | +150 | 40.0% |
| 2/1 | 3.00 | +200 | 33.3% |
| 5/2 | 3.50 | +250 | 28.6% |
| 4/1 | 5.00 | +400 | 20.0% |
| 10/1 | 11.00 | +1000 | 9.1% |
| 20/1 | 21.00 | +2000 | 4.8% |
How do you convert fractional odds to decimal and American?
To get decimal odds, divide the fraction and add 1, so 5/2 is 2.5 + 1 = 3.50. To get American odds, multiply the profit per unit by 100 for a positive price, or divide 100 by it for a negative price. The chart gives the five formulas in one box.
- Fractional to decimal: n/d + 1. For 5/2 the answer is 3.50.
- Decimal to fractional: decimal minus 1. For 3.50 the answer is 2.50, which is 5/2.
- Decimal to American, underdog (+): (decimal minus 1) x 100. For 3.50 the answer is +250.
- Decimal to American, favorite (-): -100 / (decimal minus 1). For 1.50 the answer is -200.
- Hong Kong odds: decimal minus 1, so 3.50 is 2.50 profit per 1 staked.
How do you turn odds into an implied probability?
Divide 1 by the decimal price. A price of 4.00 gives 1 / 4, which is 25%. For fractional odds n/d, use d / (n + d). For American odds, use 100 / (X + 100) when the price is +X, and X / (X + 100) when it is -X.
| Price | Working | Implied probability |
|---|---|---|
| 5/2 | 2 / (5 + 2) | 28.6% |
| 1.50 | 1 / 1.50 | 66.7% |
| +250 | 100 / (250 + 100) | 28.6% |
| -110 | 110 / (110 + 100) | 52.4% |
Why do implied probabilities add up to more than 100%?
A bookmaker builds a margin, called the overround, into every price. That pushes the implied probabilities of all outcomes in a market above 100% in total. The bigger the total, the more the market costs you. The chart includes a worked example you can copy.
Take an even contest with 1.91 on both sides. Each side implies 1 / 1.91 = 52.36%, so the total is 104.71% and the margin is 4.71%. Divide each side by 1.0471 to remove it and you get 50.00% each, which is a fair price of 2.00. A three-way market priced 2.10, 3.40 and 3.60 adds up to 104.81%.
What mistakes do people make when converting odds?
The most common mistake is mixing up profit and total return. Fractional odds show profit per unit staked. Decimal odds show the total return, with your stake included. The same slip causes most conversion errors, so check which one you are reading first.
- A decimal price of 1.00 returns only your stake, so it can never show a profit.
- A negative American number is not a negative probability. -200 means you stake 200 to win 100, an implied chance of 66.7%.
- Rounded charts differ by a point or two. For example, 8/13 is exactly -162.5 in American odds and shows as -163 on a rounded chart.
- The implied probability is not the true chance. It includes the margin, so it is a little higher than a fair figure.
What should you do with the result?
Use the chart to read prices correctly and see what they cost, not to decide that a bet is worth making. Every price carries a margin, and a high implied chance does not make an outcome certain. Set a limit before you play, and see our safer play toolkit if you want help with that.
To check a price that is not on the chart, try the odds converter or the implied probability calculator.
How to read the result
Find your price in any column and read across. The Implied probability column is the chance the price needs to be right to break even. It includes the bookmaker margin, so it is a little higher than the true chance. American figures are rounded to the nearest whole number.
How it is calculated
Decimal = fractional (n/d) + 1. Implied probability = 1 / decimal, or d / (n + d) for fractional odds. American positive = (decimal - 1) x 100. American negative = -100 / (decimal - 1). Hong Kong = decimal - 1. Overround = sum of implied probabilities - 100%. All 46 rows were computed in code from the fractions.
Worked example
Worked example
Odds 5/2. Decimal: 5 / 2 + 1 = 3.50. American: (3.50 - 1) x 100 = +250. Implied probability: 2 / (5 + 2) = 28.6%. Two sides both priced 1.91: each implies 52.36%, the total is 104.71% and the margin is 4.71%. Removing it gives a fair price of 2.00 on each side.
Limits
The chart converts and explains prices. It does not say whether a price is fair or a bet is worth making. Prices are rounded and real prices vary slightly. It does not cover Malay or Indonesian odds, and it does not allow for fees, tax, dead heats or rule differences. Results are estimates of what a price means, not predictions.