Odds Converter: American, Decimal, Fractional & Implied Probability
A free odds converter that instantly translates between American, decimal, and fractional formats. See the implied probability and $100 payout for any odds in one click.
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Quick reference — common odds
| American | Decimal | Fractional | Implied Prob | $100 Payout |
|---|---|---|---|---|
| −500 | 1.20 | 1/5 | 83.3% | $120.00 |
| −300 | 1.33 | 1/3 | 75.0% | $133.33 |
| −200 | 1.50 | 1/2 | 66.7% | $150.00 |
| −150 | 1.67 | 2/3 | 60.0% | $166.67 |
| −110 | 1.91 | 10/11 | 52.4% | $190.91 |
| +100 | 2.00 | 1/1 | 50.0% | $200.00 |
| +110 | 2.10 | 11/10 | 47.6% | $210.00 |
| +150 | 2.50 | 3/2 | 40.0% | $250.00 |
| +200 | 3.00 | 2/1 | 33.3% | $300.00 |
| +300 | 4.00 | 3/1 | 25.0% | $400.00 |
| +500 | 6.00 | 5/1 | 16.7% | $600.00 |
| +1000 | 11.00 | 10/1 | 9.1% | $1100.00 |
Conversions use standard formulas: American positive → Decimal = (odds / 100) + 1; American negative → Decimal = (100 / |odds|) + 1. Implied probability = (1 / decimal odds) × 100. This does not account for the vig (juice) — actual probabilities are slightly higher than implied odds suggest. Click any row to populate the converter.
The short answer
The converter above takes odds in any format — American, decimal, or fractional — and instantly shows you the equivalent in all three, plus the implied probability and what a $100 bet would pay. No mental math, no memorizing formulas. Type the number, see the answer.
Key takeaway: All three odds formats describe the same thing: the ratio between your stake and your potential profit. -110, 1.909, and 10/11 are three ways of writing the exact same bet. The converter proves it — enter any one, and the other two appear automatically.
How to use the converter
- Pick the format you have — American, decimal, or fractional.
- Type the odds — the number from your sportsbook or betting slip.
- Read the results — all three formats, implied probability, and the payout on a $100 stake.
- Use the reference table — common odds are pre-calculated below the converter for quick lookup.
How odds conversion works
The three formats are just different notations for the same underlying number: the decimal odds. Everything converts through decimal as the common language.
American → Decimal:
- Positive (+200): decimal = (american / 100) + 1 = 3.00
- Negative (-110): decimal = (100 / |american|) + 1 = 1.909
Decimal → Fractional:
- Subtract 1, then express as a fraction. Decimal 3.00 → 2/1. Decimal 1.909 → 10/11.
Decimal → Implied Probability:
- 1 / decimal × 100. Decimal 1.909 → 52.4% implied probability.
The converter handles all of this automatically. For a full walkthrough of each format with worked examples, see our guide on how betting odds work. The odds formats lesson covers the same material as part of the sports betting course.
Why do different formats exist?
History and geography. American odds evolved from US bookmaking traditions where the baseline is $100. Decimal odds are the global standard because the math is simplest — multiply stake by odds, done. Fractional odds come from British horse racing, where a "6/4 shot" tells you the profit-to-stake ratio directly.
Most modern sportsbooks let you toggle between formats in their settings. But when you're comparing lines across books — especially international ones — the converter saves time. Enter the number, see the comparison.
What is implied probability?
Implied probability is the win percentage the odds encode. At -110 (decimal 1.909), the sportsbook is pricing the outcome at 52.4%. At +200 (decimal 3.00), it's 33.3%.
The important thing: implied probabilities on both sides of a market always add up to more than 100%. The excess is the vig — the sportsbook's built-in margin. On a standard -110/-110 market, both sides imply 52.4%, totaling 104.8%. The extra 4.8% is what the book keeps.
Understanding implied probability is the first step toward identifying value bets — situations where you believe the true probability is higher than what the odds imply.
How is this different from the payout calculator?
The odds converter focuses on format translation and probability. Our odds payout calculator focuses on calculating the exact dollar payout for a specific stake. Use the converter when you need to understand what odds mean; use the payout calculator when you need to know what a specific bet pays.
What should I learn next?
- How Betting Odds Work: Full guide to all three formats with worked examples
- Odds Payout Calculator: Calculate exact payouts for any stake
- Parlay Calculator: Calculate multi-leg bet payouts
- Implied Probability: Deep dive into probability and the vig
- Sports Betting Fundamentals Course: The full structured course
About the author
Trust & Responsible Play Writer
Marcus focuses on judging casinos before you deposit — licensing checks, red flags, scam patterns — and the bankroll habits and limit tools that keep play under control.