How it works
Odds are one price written in different ways. Decimal odds are the total return per unit staked, so 2.50 pays 2.50 for every 1. Fractional odds are the profit over the stake: 3/2 pays 3 for every 2. American odds are the profit on 100 when positive (+150) and the stake needed to win 100 when negative (−200). The implied probability is 1 divided by the decimal odds.
The chance a price implies still includes the bookmaker’s margin, which is why the chances across a whole market add up to more than 100%. To take the margin out, use the implied probability and margin calculator.
The formula
- Decimal = 1 + numerator ÷ denominator
- American = (decimal − 1) × 100 from 2.00 up, and −100 ÷ (decimal − 1) below 2.00
- Implied probability = 1 ÷ decimal
- Hong Kong = decimal − 1
A worked football example
A home win priced at 2.50 is 3/2 in fractional and +150 in American, and implies a 40.0% chance. The away win at 1.80 is 4/5, −125 and 55.6%.
What it does not tell you
Converting odds never changes the bet: 3/2, 2.50 and +150 pay exactly the same. The implied probability is the bookmaker’s view with its margin left in, not the real chance of the result.
Odds conversion table
| Fractional | Decimal | American | Implied probability |
|---|---|---|---|
| 1/5 | 1.20 | −500 | 83.3% |
| 1/4 | 1.25 | −400 | 80.0% |
| 1/3 | 1.33 | −300 | 75.0% |
| 2/5 | 1.40 | −250 | 71.4% |
| 1/2 | 1.50 | −200 | 66.7% |
| 4/6 | 1.67 | −150 | 60.0% |
| 4/5 | 1.80 | −125 | 55.6% |
| 10/11 | 1.91 | −110 | 52.4% |
| Evens (1/1) | 2.00 | +100 | 50.0% |
| 6/5 | 2.20 | +120 | 45.5% |
| 11/8 | 2.38 | +138 | 42.1% |
| 6/4 | 2.50 | +150 | 40.0% |
| 7/4 | 2.75 | +175 | 36.4% |
| 2/1 | 3.00 | +200 | 33.3% |
| 9/4 | 3.25 | +225 | 30.8% |
| 5/2 | 3.50 | +250 | 28.6% |
| 3/1 | 4.00 | +300 | 25.0% |
| 7/2 | 4.50 | +350 | 22.2% |
| 4/1 | 5.00 | +400 | 20.0% |
| 9/2 | 5.50 | +450 | 18.2% |
| 5/1 | 6.00 | +500 | 16.7% |
| 6/1 | 7.00 | +600 | 14.3% |
| 7/1 | 8.00 | +700 | 12.5% |
| 8/1 | 9.00 | +800 | 11.1% |
| 10/1 | 11.00 | +1,000 | 9.1% |
| 12/1 | 13.00 | +1,200 | 7.7% |
| 16/1 | 17.00 | +1,600 | 5.9% |
| 20/1 | 21.00 | +2,000 | 4.8% |
| 33/1 | 34.00 | +3,300 | 2.9% |
| 50/1 | 51.00 | +5,000 | 2.0% |
| 100/1 | 101.00 | +10,000 | 1.0% |
Common questions
How do I convert fractional odds to decimal?
Divide the first number by the second and add 1. 5/2 is 5 ÷ 2 + 1 = 3.50, and 4/6 is 4 ÷ 6 + 1 = 1.67.
What do plus and minus mean in American odds?
A plus number is the profit on a stake of 100: +150 wins 150. A minus number is the stake needed to win 100: −200 means staking 200 to win 100. Evens is +100.
How do I work out implied probability from odds?
Divide 1 by the decimal odds: 2.50 implies 1 ÷ 2.50 = 40%. For fractional odds a/b the implied probability is b ÷ (a + b), so 3/1 is 1 ÷ 4 = 25%.
Why does 1.91 show as 10/11 on a bookmaker’s board?
1.91 is exactly 91/100, but British boards print a ladder of traditional fractions, and 10/11 (1.909) is the nearest. The converter shows the exact fraction and the nearest board price separately.
What are Hong Kong, Malay and Indonesian odds?
Asian formats. Hong Kong odds are the profit per unit: decimal minus 1. Malay odds are the same up to 1.00 and turn negative above it, as minus the stake needed to win one unit. Indonesian odds are American odds divided by 100.