Odds converter
Type a price in any format: the other two and the implied probability update as you type.
How to use the converter
- Type the price into the box for the format you have: decimal such as 2.50 (a comma works as well as a point), American such as +150 or -110, or fractional such as 3/2.
- The other two boxes and the implied probability change as you type. There is no button to press, and the numbers never leave this page.
- Read the profit line: it shows what a winning bet of 10 makes on top of the stake, in whatever currency you bet in.
American prices need their sign and a value of at least 100, so +150 and -110 work, while 150 typed without a sign is read as decimal odds of 150. Decimal odds have to be above 1.00, because a price of exactly 1.00 would only hand your stake back. If a price cannot be read, a short note under the boxes says so and shows the formats that work.
The formulas
- American +X to decimal = X / 100 + 1
- American -X to decimal = 100 / X + 1
- Fractional A/B to decimal = A / B + 1
- Implied probability = 1 / decimal odds
| Decimal | American | Fractional | Implied |
|---|---|---|---|
| 1.50 | -200 | 1/2 | 66.7% |
| 1.91 | -110 | 10/11 | 52.4% |
| 2.00 | +100 | 1/1 | 50.0% |
| 2.50 | +150 | 3/2 | 40.0% |
| 3.00 | +200 | 2/1 | 33.3% |
| 5.00 | +400 | 4/1 | 20.0% |
Worked examples
- -110 to decimal: 100 / 110 + 1 = 1.91. A winning 10 stake returns 19.09, a profit of 9.09, and the implied probability is 1 / 1.909 = 52.4%.
- 5/2 to decimal: 5 / 2 + 1 = 3.50, which is +250 in American odds and an implied probability of 28.6%.
- Decimal 1.25 to American: below 2.00 the American price is negative, and 100 / (1.25 - 1) = 400, so the price is -400, or 1/4 as a fraction, with an implied 80%.
What implied probability tells you
Implied probability is the price turned into a chance, and it works as a break-even line. At decimal 2.50 a bet has to win 40% of the time just to hand back what was staked over a long run of bets. If you rate a team's chances above the implied figure, the price looks generous to you; below it, the price looks mean. Either way the figure still contains the bookmaker's margin, so the chance the market is really pricing sits a little below the number shown.
Taking the margin out
Add up the implied probabilities of every outcome in a market to see its margin. A football match priced at 2.10 for the home side, 3.40 for the draw and 3.60 for the away side gives 47.6% + 29.4% + 27.8% = 104.8%, so the book carries a margin of about 4.8%. Divide each probability by 1.048 to spread that margin back out and you get roughly 45.4%, 28.1% and 26.5%, which are fair odds of about 2.20, 3.56 and 3.77. This proportional method is the simplest one; a bookmaker may not load its margin evenly across outcomes, so treat the fair prices as an estimate rather than the market's true view.
Questions players ask
How do I convert American odds to decimal?
Positive American odds: divide by 100 and add 1 (+150 = 2.50). Negative: divide 100 by the odds without the minus and add 1 (-200 = 1.50).
What is implied probability?
The chance the price suggests, before the bookmaker margin is removed: 1 divided by the decimal odds. Odds of 2.00 imply 50%.
Why do both sides of a bet add up to more than 100%?
That extra is the bookmaker margin. Two sides at -110 each imply 52.4%, together 104.8%: the 4.8% is the margin.
What do the plus and minus signs in American odds mean?
A minus sign shows the stake needed to win 100: at -200 you stake 200 to make 100 profit, which is decimal 1.50. A plus sign shows the profit on a 100 stake: +200 makes 200 profit, decimal 3.00. Prices between -100 and +100 do not exist in American notation, so the converter refuses them.
Why does the fractional price differ from my bookmaker?
The converter rounds to the closest fraction with a bottom number of 100 or less, working from the decimal price shown. Decimal 1.62 therefore comes back as 31/50, while a bookmaker would usually print the traditional 8/13, which is 1.615. Both describe almost exactly the same price.