Every price says two things. It tells you what you get back if the bet wins, and it tells you the chance the bookmaker is putting on the outcome. The three formats you will see, decimal, fractional and American, say exactly the same thing in different ways.
Decimal odds
Decimal is the format we use across OddAlerts, because it is the easiest to do sums with. The number is the total return per 1 unit staked, and that total includes your stake.
- 2.00 on a £10 bet returns £20. That is £10 profit plus the £10 stake.
- 3.50 on £10 returns £35, so £25 profit.
- 1.25 on £10 returns £12.50, so £2.50 profit.
Profit is always the stake times the odds minus one. A price below 2.00 is "odds-on": you risk more than you can win.
Fractional odds
Fractional odds are the traditional UK format. They show the profit only, as a fraction of the stake. 5/2 means £5 profit for every £2 staked. Evens, written 1/1, means you win what you staked.
To convert to decimal, divide the top by the bottom and add 1. 5/2 is 2.5, plus 1, so 3.50. 1/4 is 0.25, plus 1, so 1.25. 6/4 is 2.50.
American odds
American odds, also called moneyline, use 100 as the reference point.
- A plus number is the profit on a 100 stake. +150 wins 150, so it is 2.50 in decimal.
- A minus number is the stake needed to win 100. −200 needs 200 to win 100, so it is 1.50 in decimal.
To convert a plus price, divide by 100 and add 1. For a minus price, divide 100 by the number (ignore the minus sign) and add 1.
| Decimal | Fractional | American | Implied chance |
|---|---|---|---|
| 1.50 | 1/2 | −200 | 66.7% |
| 2.00 | 1/1 (evens) | +100 | 50% |
| 2.50 | 6/4 | +150 | 40% |
| 3.00 | 2/1 | +200 | 33.3% |
| 5.00 | 4/1 | +400 | 20% |
Turning odds into a chance
This is the part that actually matters for betting. One divided by the decimal odds is the implied probability. 2.50 implies 40%. 1.50 implies 66.7%.
Once a price is a percentage, you can compare it with the chance you give the outcome. If our model gives a team 48% and the best price implies 40%, the price is longer than the model thinks it should be. That gap is the whole idea behind a value bet. Add up the implied chances of every outcome in a market and you will get more than 100%. The extra is the bookmaker's margin.
The odds calculator converts between the three formats and shows the implied chance, if you would rather not do the sums.
FAQ
What does 2/1 mean in decimal odds?
3.00. Divide 2 by 1 and add 1. A £10 bet at 2/1 returns £30, which is £20 profit plus the £10 stake.
Do decimal odds include the stake?
Yes. Decimal odds are the total return per unit staked. Fractional and American odds show the profit only.
What does a minus sign mean in American odds?
The selection is odds-on. −150 means you stake 150 to win 100, which is 1.67 in decimal.
Related Terms
Implied probability is the chance hidden in any price. A value bet is a price whose implied chance is lower than yours. Dropping odds are prices getting shorter, which raises the implied chance.