Fractional odds are the traditional British format and still appear in horse racing, golf, futures markets and sports media. US sportsbooks rarely use them, but you will see them often enough that it is worth knowing how to read and convert them.
How fractional odds work
A fraction like 5/1 (said "five to one") tells you profit relative to stake: you win 5 units for every 1 unit you bet.
- 5/1: bet $10, win $50 profit, $60 back
- 11/10: bet $10, win $11 profit, $21 back
- 4/6: bet $6, win $4 profit, $10 back
- 1/1 ("evens"): win what you risk
When the first number is bigger, the bet is an underdog (odds against). When it is smaller, it is a favorite (odds on).
Converting fractional odds
For a fraction A/B:
- Decimal = A ÷ B + 1 (5/1 → 6.00; 4/6 → 1.667)
- American, if A ≥ B: +(A ÷ B × 100) (5/1 → +500)
- American, if A < B: −(B ÷ A × 100) (4/6 → −150)
- Implied probability = B ÷ (A + B) (5/1 → 1/6 = 16.7%; 4/6 → 6/10 = 60%)
The odds converter handles all formats.
Conversion table
| Fractional | Decimal | American | Implied |
|---|---|---|---|
| 1/4 | 1.25 | −400 | 80.0% |
| 1/2 | 1.50 | −200 | 66.7% |
| 4/6 | 1.67 | −150 | 60.0% |
| 10/11 | 1.91 | −110 | 52.4% |
| 1/1 | 2.00 | +100 | 50.0% |
| 6/4 | 2.50 | +150 | 40.0% |
| 2/1 | 3.00 | +200 | 33.3% |
| 5/1 | 6.00 | +500 | 16.7% |
| 10/1 | 11.00 | +1000 | 9.1% |
| 100/1 | 101.00 | +10000 | 1.0% |
Where you will see fractional odds
- Futures like "Team X 12/1 to win the championship"
- Golf outrights, where longshots dominate (Golf betting guide)
- Horse racing and UK/Irish media
- Novelty markets
When comparing a futures price quoted as 12/1 in an article with +1100 at your book, convert first: 12/1 is +1200, so the article's price is better. (Futures betting value.)
Why fractional odds hide the margin
Fractions are awkward to add up, which makes it hard to see how much margin is baked into a market. Convert each price to implied probability and add them. In a 20-runner golf or racing market the total often reaches 120–150%, far more margin than a −110 spread. (Sportsbook hold.)
Frequently asked questions
What does 7/2 mean in betting?
You win $7 for every $2 staked, which is decimal 4.50 or +350 American. Implied probability is 22.2%.
What does 1/2 mean in odds?
A favorite: you win $1 for every $2 staked. It equals −200 American and a 66.7% implied chance.
Is 11/10 good odds?
11/10 equals +110. Whether it is good depends on the true probability; it is a value if the outcome wins more than 47.6% of the time.