How to convert odds
All three formats say the same thing in different ways: how much you win for what you risk.
- Decimal odds (Europe, Australia, Canada): the total return per unit staked, stake included. At 2.50 a stake of 10 returns 25, a profit of 15.
- Fractional odds (UK and Ireland): profit relative to the stake. At 3/2 you win 3 for every 2 you stake.
- American odds (US): positive numbers show the profit on a 100 stake (+150 wins 150); negative numbers show the stake needed to win 100 (−200 means risking 200 to win 100).
The formulas
| From | To decimal | Example |
|---|---|---|
| Fractional a/b | 1 + a ÷ b | 3/2 → 1 + 3 ÷ 2 = 2.50 |
| American +x | 1 + x ÷ 100 | +150 → 1 + 1.50 = 2.50 |
| American −x | 1 + 100 ÷ x | −200 → 1 + 0.50 = 1.50 |
| Decimal d → fractional | (d − 1) as a fraction | 2.50 → 1.50 = 3/2 |
| Decimal d → American | d ≥ 2: (d − 1) × 100; d < 2: −100 ÷ (d − 1) | 2.50 → +150, 1.50 → −200 |
Odds conversion chart
| Decimal | Fractional | American | Implied probability |
|---|---|---|---|
| 1.20 | 1/5 | −500 | 83.3% |
| 1.25 | 1/4 | −400 | 80.0% |
| 1.33 | 1/3 | −300 | 75.0% |
| 1.50 | 1/2 | −200 | 66.7% |
| 1.67 | 2/3 | −150 | 60.0% |
| 1.91 | 10/11 | −110 | 52.4% |
| 2.00 | 1/1 (evens) | +100 | 50.0% |
| 2.25 | 5/4 | +125 | 44.4% |
| 2.50 | 3/2 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 4.00 | 3/1 | +300 | 25.0% |
| 5.00 | 4/1 | +400 | 20.0% |
| 7.00 | 6/1 | +600 | 14.3% |
| 11.00 | 10/1 | +1,000 | 9.1% |
Decimal values are rounded to two places: 1/3 is exactly 1.3333 and 2/3 is exactly 1.6667.
Converting odds to probability
The implied probability of any price is 1 ÷ decimal odds: 2.50 implies 40%. It includes the bookmaker's margin, so it overstates the real chance; see implied probability and what is the vig. To remove the margin and get a fair price, use the no-vig calculator, which also reads all three formats.
Which format do bookmakers use?
It's mostly a matter of region and tradition. Decimal is the most common across Europe, Australia and Canada and is what most betting maths uses; fractional is traditional in UK and Irish horse racing and often still offered there; American odds are standard in US sportsbooks. Most bookmakers let you switch format in their settings.