What is an odds converter?
An odds converter turns betting odds from one format into another — decimal, fractional, American (moneyline) and implied probability. The four formats describe the exact same thing in different ways, so converting lets you compare odds across bookmakers and regions and instantly see the probability the odds imply.
The four odds formats
Decimal
Total return per 1 unit staked, stake included. 2.50 returns 2.50. (Europe)
Fractional
Profit vs stake. 3/2 = 3 profit per 2 staked. (UK & Ireland)
American
+150 profit on a 100 stake; −200 stake to win 100. (US)
Implied probability
The chance the odds imply: 1 ÷ decimal × 100. 2.00 = 50%.
How to convert odds manually
Every format is just a different way of writing the same probability, so you can convert between any of them with simple maths. Decimal is the easiest to work from:
- Decimal → implied probability: 1 ÷ decimal × 100. (2.50 → 40%)
- Decimal → fractional: decimal − 1, written as a fraction. (2.50 → 3/2)
- Decimal → American: (decimal − 1) × 100 if decimal ≥ 2, otherwise −100 ÷ (decimal − 1). (2.50 → +150)
- Fractional → decimal: divide the fraction and add 1. (3/2 → 1.5 + 1 = 2.50)
- American → decimal: positive: (American ÷ 100) + 1; negative: (100 ÷ |American|) + 1. (+150 → 2.50)
- Implied probability → decimal: 100 ÷ probability. (40% → 2.50)
Working out arbitrage? Once your odds are in decimal, drop them into the surebet calculator. Want to know what a bet pays? Use the odds payout calculator.
Odds conversion table
A quick reference for the most common betting odds across all four formats — decimal, fractional, American (moneyline) and implied probability.
| 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% |
| 2.00 | 1/1 (evens) | +100 | 50.0% |
| 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% |
| 6.00 | 5/1 | +500 | 16.7% |
| 11.00 | 10/1 | +1000 | 9.1% |
Decimal, fractional and American odds: what's the difference?
The three formats are regional conventions for the same numbers. Decimal odds (also called European odds) dominate in Europe and Australia. Fractional odds are the traditional UK and Irish style. American odds (moneyline) are standard in the US. A good betting odds converter lets you read any bookmaker's price in the format you're comfortable with and instantly see the implied probability behind it — the number that actually tells you whether a bet offers value.
Learn more about arbitrage betting
New to this? Read our full guide on what is arbitrage betting, or see the arbitrage betting formula explained step by step with worked examples.
Frequently asked questions
- What are decimal odds?
- Decimal odds show the total return per 1 unit staked, including your stake. Odds of 2.50 return 2.50 for every 1 staked (1.50 profit). Common in Europe.
- What are fractional odds?
- Fractional odds (e.g. 3/2) show profit relative to stake: 3/2 means 3 profit for every 2 staked. Common in the UK and Ireland.
- What are American (moneyline) odds?
- Positive American odds (+150) show the profit on a 100 stake. Negative odds (−200) show how much you must stake to win 100. Common in the US.
- What is implied probability?
- Implied probability is the chance of an outcome suggested by the odds: 1 ÷ decimal odds × 100. Odds of 2.00 imply a 50% chance.
- Which odds format is best?
- They are mathematically identical — it is just presentation. Decimal is the easiest for calculating returns and comparing value, which is why most bettors and our calculators use it.
- How do I convert American odds to decimal?
- For positive American odds, divide by 100 and add 1: +150 becomes (150 ÷ 100) + 1 = 2.50. For negative odds, divide 100 by the number (ignoring the minus sign) and add 1: −200 becomes (100 ÷ 200) + 1 = 1.50.
- What is 2/1 in decimal odds?
- 2/1 (two-to-one) equals 3.00 in decimal. You divide the fraction (2 ÷ 1 = 2) and add 1 to include your returned stake, giving 3.00 — an implied probability of 33.3%.